1 00:00:08,375 --> 00:00:09,975 [Alan] Equipment wise, and weather wise, 2 00:00:10,010 --> 00:00:11,677 you psychologically prepare yourself 3 00:00:11,711 --> 00:00:13,012 because with all best intentions 4 00:00:13,046 --> 00:00:14,780 you can plan an expedition for two years, 5 00:00:14,814 --> 00:00:16,982 and you go there and it just goes wrong. 6 00:00:17,017 --> 00:00:18,584 [Victor] Sailors were actually terrified 7 00:00:18,618 --> 00:00:19,585 to come to this area 8 00:00:19,619 --> 00:00:20,652 because it was so dangerous. 9 00:00:20,687 --> 00:00:22,454 And ships did not return. 10 00:00:22,489 --> 00:00:24,656 [Alan] Just watch that arm. 11 00:00:24,691 --> 00:00:27,926 [Kelvin] Up on the towline a little bit! 12 00:00:27,961 --> 00:00:28,994 [bleep] it! 13 00:00:29,029 --> 00:00:30,029 Oh [bleep] 14 00:00:33,033 --> 00:00:34,266 [Patrick] LF. 15 00:00:35,435 --> 00:00:38,237 LF. Comms check. Comms check. 16 00:00:39,506 --> 00:00:43,575 He didn't hear me. He didn't acknowledge. 17 00:00:43,610 --> 00:00:46,011 [dramatic music playing] 18 00:00:46,046 --> 00:00:47,813 [Demetri] Humankind has explored 19 00:00:47,847 --> 00:00:50,816 every continent on Earth. 20 00:00:50,850 --> 00:00:54,787 Climbed its tallest mountains. 21 00:00:54,821 --> 00:00:58,157 And even journeyed into space. 22 00:00:58,191 --> 00:00:59,691 [man] Thank you, Mr. President. 23 00:00:59,726 --> 00:01:02,227 [Demetri] But there's a vast swathe of our own planet 24 00:01:02,262 --> 00:01:05,230 that has remained a mystery. 25 00:01:05,265 --> 00:01:08,801 [dramatic music playing] 26 00:01:08,835 --> 00:01:11,403 [Demetri] The deep ocean. 27 00:01:11,438 --> 00:01:15,774 Stretching down over 35,000 feet into crushing pressures, 28 00:01:15,809 --> 00:01:18,644 it's been near impossible to reach. 29 00:01:18,678 --> 00:01:20,045 Until now. 30 00:01:21,948 --> 00:01:23,582 New engineering breakthroughs 31 00:01:23,616 --> 00:01:26,185 are driving an audacious global mission 32 00:01:26,219 --> 00:01:29,655 to dive to the deepest points of all the five oceans, 33 00:01:29,689 --> 00:01:32,758 for the first time in history. 34 00:01:32,792 --> 00:01:35,861 These pioneers will push technology to the limit... 35 00:01:35,895 --> 00:01:38,931 - What the hell was that? - We have a leaking hatch. 36 00:01:38,965 --> 00:01:41,100 [Demetri] ...to open up this final frontier 37 00:01:41,134 --> 00:01:42,968 as never before. 38 00:01:43,002 --> 00:01:45,504 [Casie] Trying to mentally put yourself at the bottom 39 00:01:45,538 --> 00:01:46,972 is just mind-blowing. 40 00:01:47,006 --> 00:01:49,108 [Demetri] Mapping hidden landscapes, 41 00:01:49,142 --> 00:01:51,310 discovering unknown lifeforms. 42 00:01:51,344 --> 00:01:54,446 [Alan] What on Earth is that? 43 00:01:54,481 --> 00:01:56,515 And unlocking the secrets of how life 44 00:01:56,549 --> 00:01:58,050 in the extreme deep ocean 45 00:01:58,084 --> 00:02:00,486 affects our entire planet. 46 00:02:00,520 --> 00:02:03,522 [dramatic music playing] 47 00:02:13,666 --> 00:02:15,300 [Stuart] Okay, Alan, good to go. 48 00:02:15,335 --> 00:02:17,369 [Alan D] Good to go. 49 00:02:17,403 --> 00:02:20,105 [Demetri] Extreme explorer and ex-naval commander 50 00:02:20,140 --> 00:02:21,373 Victor Vescovo 51 00:02:21,407 --> 00:02:23,108 is putting his life on the line, 52 00:02:23,143 --> 00:02:24,776 as well as 50 million dollars 53 00:02:24,811 --> 00:02:27,713 of his own money to pursue his dream. 54 00:02:27,747 --> 00:02:28,680 Good boy. 55 00:02:28,715 --> 00:02:30,048 What little boy or little girl 56 00:02:30,083 --> 00:02:32,885 doesn't grow up wanting to be an explorer? 57 00:02:32,919 --> 00:02:34,987 And here I am with a wonderful ship, a great crew, 58 00:02:35,021 --> 00:02:37,589 it's now the deepest diving submersible in the world 59 00:02:37,624 --> 00:02:39,324 and I get to play in the ocean with it 60 00:02:39,359 --> 00:02:41,393 and discover things that have never been seen before. 61 00:02:41,427 --> 00:02:44,863 How could you not be absolutely ecstatic? 62 00:02:44,898 --> 00:02:46,665 [Demetri] His mission is to travel to each 63 00:02:46,733 --> 00:02:50,102 of the five oceans, discover their deepest point 64 00:02:50,136 --> 00:02:52,704 and unlock their unexplored secrets. 65 00:02:52,739 --> 00:02:55,440 He has already travelled over five miles down 66 00:02:55,475 --> 00:02:57,643 to the very bottom of the Atlantic Ocean. 67 00:02:57,677 --> 00:02:59,211 [Victor] Oh, my goodness. I can see the bottom. 68 00:03:02,415 --> 00:03:04,327 [Demetri] Now he and his team are heading 69 00:03:04,351 --> 00:03:06,919 for a far tougher challenge. 70 00:03:09,689 --> 00:03:11,990 The Southern Ocean. 71 00:03:12,025 --> 00:03:16,328 It surrounds the frozen continent of Antarctica. 72 00:03:16,362 --> 00:03:19,198 These are the coldest waters on the planet 73 00:03:19,232 --> 00:03:21,099 and some of the roughest seas, 74 00:03:21,134 --> 00:03:23,435 making it perhaps the most dangerous 75 00:03:23,469 --> 00:03:25,771 of all the Earth's oceans. 76 00:03:25,805 --> 00:03:29,041 [Victor] Some of the old-style maps had "here be dragons" 77 00:03:29,075 --> 00:03:30,709 and sailors were actually terrified 78 00:03:30,743 --> 00:03:32,778 to come to this area because it was so dangerous. 79 00:03:32,812 --> 00:03:34,313 And ships did not return. 80 00:03:34,347 --> 00:03:35,781 They would be destroyed. 81 00:03:35,815 --> 00:03:38,817 [suspenseful music playing] 82 00:03:42,622 --> 00:03:44,890 [Demetri] Rising winds are already testing 83 00:03:44,924 --> 00:03:47,793 the crew and equipment. 84 00:03:47,827 --> 00:03:49,928 Getting a little brisk out here, all right. 85 00:03:49,963 --> 00:03:52,664 It's lovely. Might have to take the shorts off. 86 00:03:52,699 --> 00:03:56,568 [laughs] Will have to go to long pants soon. 87 00:03:56,603 --> 00:03:59,805 [man] Boy, it came up [bleep] quick, huh? 88 00:03:59,839 --> 00:04:01,173 [Patrick] Kelvin, you need more straps? 89 00:04:01,207 --> 00:04:04,209 [suspenseful music playing] 90 00:04:07,480 --> 00:04:09,047 [Demetri] Soon, they're experiencing 91 00:04:09,082 --> 00:04:10,816 a full-scale snowstorm. 92 00:04:10,850 --> 00:04:12,484 [Patrick] [bleep] me. 93 00:04:14,354 --> 00:04:17,122 [Stuart] It should be dead ahead somewhere. 94 00:04:17,156 --> 00:04:19,358 I'll just lower the starboard a little bit. 95 00:04:21,461 --> 00:04:22,961 Yeah, I got it. 96 00:04:22,996 --> 00:04:25,130 [Victor] In this life, I'd rather be lucky than good. 97 00:04:25,164 --> 00:04:26,465 And when it comes to weather, 98 00:04:26,499 --> 00:04:28,967 you definitely want to be lucky. 99 00:04:29,002 --> 00:04:31,570 [Demetri] Victor is worried about the effects of the cold 100 00:04:31,604 --> 00:04:35,507 on the expedition's vital navigation equipment. 101 00:04:35,541 --> 00:04:37,509 Batteries look okay. 102 00:04:37,543 --> 00:04:38,610 Modems. 103 00:04:40,480 --> 00:04:42,714 Yeah, these guys did well. 104 00:04:42,749 --> 00:04:46,985 Very strange seeing snow on my landers. 105 00:04:47,020 --> 00:04:49,187 [Demetri] The snowstorm has been an early warning 106 00:04:49,222 --> 00:04:52,224 of the treacherous weather that could lie ahead. 107 00:04:52,258 --> 00:04:57,262 [indistinct radio chatter] 108 00:04:57,297 --> 00:04:59,865 [Demetri] To search for the ocean's deepest point, 109 00:04:59,899 --> 00:05:02,301 Victor and his team are heading for a dramatic 110 00:05:02,335 --> 00:05:06,605 underwater chasm called the South Sandwich Trench. 111 00:05:08,608 --> 00:05:11,810 [Demetri] Over four and a half miles deep, 112 00:05:11,844 --> 00:05:14,046 its waters drop below freezing 113 00:05:14,080 --> 00:05:16,948 and are under huge pressure. 114 00:05:16,983 --> 00:05:21,386 Five times the crushing power of a junkyard car compactor. 115 00:05:21,421 --> 00:05:23,422 [Victor] It's very rarely visited. 116 00:05:23,456 --> 00:05:25,490 And certainly no-one has ever mapped 117 00:05:25,525 --> 00:05:27,292 the South Sandwich Trench. 118 00:05:27,327 --> 00:05:28,493 Certainly not with the kind of tools 119 00:05:28,528 --> 00:05:30,262 we will have available. So in a way, 120 00:05:30,296 --> 00:05:33,265 This is very exciting for the whole crew 121 00:05:33,299 --> 00:05:36,001 because this is true exploration. 122 00:05:36,035 --> 00:05:37,436 [Demetri] To protect Victor from 123 00:05:37,470 --> 00:05:40,005 the deadly pressures at the bottom of the trench, 124 00:05:40,039 --> 00:05:42,841 he has commissioned a remarkable prototype sub 125 00:05:42,875 --> 00:05:46,378 at a cost of 35 million dollars. 126 00:05:46,412 --> 00:05:48,347 Surrounding the cockpit is a sphere 127 00:05:48,381 --> 00:05:51,817 of 3.5-inch thick titanium 128 00:05:51,851 --> 00:05:55,954 punctured by wide-angled view ports made of acrylic. 129 00:05:55,988 --> 00:05:57,989 It's equipped with enough oxygen tanks 130 00:05:58,024 --> 00:06:01,293 to give him air for up to four days. 131 00:06:01,327 --> 00:06:04,429 But in the Southern Ocean, the sub will have to endure 132 00:06:04,464 --> 00:06:05,597 temperatures far colder 133 00:06:05,631 --> 00:06:08,233 than any it's experienced before. 134 00:06:08,267 --> 00:06:09,668 [Patrick] We'll have surface temperatures 135 00:06:09,702 --> 00:06:11,303 that are starting at zero, 136 00:06:11,337 --> 00:06:14,406 or one degree, rather than where we were before 137 00:06:14,440 --> 00:06:15,474 where the surface temperatures 138 00:06:15,508 --> 00:06:17,976 were 25 or 30 degrees Celsius. 139 00:06:18,010 --> 00:06:20,679 At depth, it'll be minus one. 140 00:06:20,713 --> 00:06:22,547 It's enough to affect our cabling, 141 00:06:22,582 --> 00:06:25,027 our connectors, our batteries. 142 00:06:25,051 --> 00:06:26,551 [Demetri] If the dive succeeds, 143 00:06:26,586 --> 00:06:28,153 the expedition scientists 144 00:06:28,187 --> 00:06:30,489 will be able to hunt for unknown creatures 145 00:06:30,523 --> 00:06:31,289 of the deep... 146 00:06:31,324 --> 00:06:33,692 [man] Prepare lights on SCAFF. 147 00:06:33,726 --> 00:06:35,093 [Demetri] ...and try to solve 148 00:06:35,128 --> 00:06:37,963 one of the Southern Ocean's greatest mysteries. 149 00:06:39,866 --> 00:06:41,466 These waters are, in fact, 150 00:06:41,501 --> 00:06:43,568 packed with oxygen and nutrients 151 00:06:43,603 --> 00:06:45,837 vital to life 152 00:06:45,872 --> 00:06:48,407 and are the source of a global ocean current 153 00:06:48,441 --> 00:06:50,809 that feeds the world. 154 00:06:50,843 --> 00:06:52,711 Scientists are desperate to find 155 00:06:52,745 --> 00:06:54,546 where this lifeblood current 156 00:06:54,580 --> 00:06:56,748 exits the Southern Ocean. 157 00:06:56,783 --> 00:07:00,318 The South Sandwich Trench is a prime suspect. 158 00:07:00,353 --> 00:07:02,254 But no-one has been able to dive 159 00:07:02,288 --> 00:07:04,322 deep enough to confirm it. 160 00:07:04,357 --> 00:07:06,958 [Oscar] The Southern Ocean, in my opinion, 161 00:07:06,993 --> 00:07:10,262 is one of the most important locations on the planet. 162 00:07:10,296 --> 00:07:12,664 It's the lungs of Earth. 163 00:07:12,698 --> 00:07:15,333 [Katherine] It's vital to global ocean circulation. 164 00:07:15,368 --> 00:07:18,837 So we need to know more. We want to know more. 165 00:07:18,871 --> 00:07:20,672 [Demetri] To make their bold attempt, 166 00:07:20,706 --> 00:07:21,840 Victor and his team 167 00:07:21,874 --> 00:07:24,142 only have a short window of time. 168 00:07:24,177 --> 00:07:26,178 The brief Antarctic summer, 169 00:07:26,212 --> 00:07:27,646 when the pack ice that locks in 170 00:07:27,680 --> 00:07:29,581 over seven million square miles 171 00:07:29,615 --> 00:07:30,560 of ocean, 172 00:07:30,584 --> 00:07:32,918 melts and retreats. 173 00:07:32,952 --> 00:07:36,221 [ice crashes] 174 00:07:36,255 --> 00:07:37,589 [Oscar] If you look at the Southern Ocean, 175 00:07:37,623 --> 00:07:38,990 every winter we grow 176 00:07:39,025 --> 00:07:42,727 almost the equivalent of the Continental United States. 177 00:07:42,762 --> 00:07:45,964 And in summer, melt that entire continent back. 178 00:07:50,036 --> 00:07:52,437 [Demetri] 100 miles away from the deepest point, 179 00:07:52,472 --> 00:07:54,973 the team sees the chance of a break in the weather 180 00:07:55,007 --> 00:07:58,210 to take the sub on an exploratory dive. 181 00:07:58,244 --> 00:08:01,112 It's an opportunity for Chief Scientist Alan Jamieson 182 00:08:01,147 --> 00:08:03,815 to search for new creatures of the deep 183 00:08:03,850 --> 00:08:06,284 and for Victor to put the sub through its paces 184 00:08:06,319 --> 00:08:11,089 in the Southern Ocean's freezing waters. 185 00:08:11,123 --> 00:08:13,658 In the spotlight is the sub's designer, 186 00:08:13,693 --> 00:08:14,826 John Ramsay. 187 00:08:14,861 --> 00:08:16,328 [John] Mechanically, everything is great 188 00:08:16,362 --> 00:08:17,629 at cold temperatures. 189 00:08:17,663 --> 00:08:19,231 It's the electrical issues 190 00:08:19,265 --> 00:08:22,033 with cold circuit boards and things like that. 191 00:08:22,068 --> 00:08:24,569 Just hoping everything's gonna be fine for the guys. 192 00:08:24,604 --> 00:08:26,338 [Demetri] First, the team needs to launch 193 00:08:26,372 --> 00:08:28,406 their 35-million-dollar sub 194 00:08:28,441 --> 00:08:31,743 off the back of a ship being buffeted by the volatile 195 00:08:31,777 --> 00:08:33,044 Southern Ocean. 196 00:08:33,079 --> 00:08:34,679 [Patrick] The most dangerous part 197 00:08:34,714 --> 00:08:35,981 of any of our operations 198 00:08:36,015 --> 00:08:38,483 will always be launch and recovery. 199 00:08:38,518 --> 00:08:39,851 That's when you're dealing 200 00:08:39,886 --> 00:08:42,254 with forces that are unpredictable, 201 00:08:42,288 --> 00:08:44,856 and managing that is a difficult thing. 202 00:08:44,891 --> 00:08:47,292 [John] Bridge, Bridge SO. We're ready to launch here. 203 00:08:47,326 --> 00:08:49,861 We're roly-poly, but we'll give it a shot. 204 00:08:51,731 --> 00:08:53,632 Okay. Let's do this. Out on the A-frame. 205 00:08:53,666 --> 00:08:56,001 Follow the tagline slowly. 206 00:08:58,771 --> 00:09:01,406 The waves are coming in behind us. 207 00:09:01,440 --> 00:09:03,575 LF, be advised, it's gonna get a little sloppy here 208 00:09:03,609 --> 00:09:04,743 for a minute. 209 00:09:04,777 --> 00:09:06,378 This is where we start to rock 'n' roll. 210 00:09:06,412 --> 00:09:07,679 Here we go, boys. 211 00:09:07,713 --> 00:09:11,283 You're gonna have to go quick. This is the worst part. 212 00:09:11,317 --> 00:09:13,184 [man] Back on the main! Back on the main! 213 00:09:13,219 --> 00:09:14,219 [man] We're out of time. 214 00:09:14,253 --> 00:09:16,254 [man] Up on the towline a little bit! 215 00:09:17,657 --> 00:09:19,257 [bleeping] 216 00:09:23,729 --> 00:09:25,630 [bleep] me. 217 00:09:25,665 --> 00:09:27,899 Just hang on. Hang on, buddy. 218 00:09:30,770 --> 00:09:34,539 Get that out on the tow line! Whoa, whoa, whoa! 219 00:09:34,574 --> 00:09:35,340 [bleeping] 220 00:09:35,374 --> 00:09:36,942 [man] Why are we doing this? 221 00:09:39,045 --> 00:09:41,479 [bleep] 222 00:09:41,514 --> 00:09:43,381 [man] Out on the tow line. 223 00:09:43,416 --> 00:09:45,216 [Patrick] To have that happen right at the moment 224 00:09:45,251 --> 00:09:46,785 you're releasing it. 225 00:09:46,819 --> 00:09:49,487 You know, that's a sickening feeling. 226 00:09:54,360 --> 00:09:55,360 [Victor] Status, please? 227 00:09:55,394 --> 00:09:56,828 [man] Just be advised, uh, 228 00:09:56,862 --> 00:10:00,332 looks like you may have lost your starboard camera. 229 00:10:00,366 --> 00:10:02,667 [Victor] Roger that. Permission to dive. 230 00:10:02,702 --> 00:10:03,768 [man] Negative, negative. 231 00:10:03,803 --> 00:10:05,870 We gotta release the towline still. 232 00:10:05,905 --> 00:10:08,440 - Okay, let's pick up the... - Yep. 233 00:10:11,110 --> 00:10:12,377 [bleep] 234 00:10:13,613 --> 00:10:15,480 [bleep] 235 00:10:16,816 --> 00:10:18,383 [Victor] What happened to the towline? 236 00:10:18,417 --> 00:10:19,985 We broke the towline. 237 00:10:20,019 --> 00:10:21,586 [man] We'll get her, Ricky. 238 00:10:21,621 --> 00:10:22,787 [Demetri] Without its tow line, 239 00:10:22,822 --> 00:10:24,923 the sub is now adrift. 240 00:10:24,957 --> 00:10:27,258 The team must clear the remaining lines 241 00:10:27,293 --> 00:10:29,060 and avoid getting freezing water 242 00:10:29,095 --> 00:10:32,230 inside their protective clothing. 243 00:10:32,264 --> 00:10:34,532 [Glenn] In the cold water of the Southern Ocean, 244 00:10:34,567 --> 00:10:37,469 if you go into the water, you've only got about a minute 245 00:10:37,503 --> 00:10:39,671 before you're in serious trouble. 246 00:10:42,808 --> 00:10:46,711 Let's get ready in case he falls in the water. 247 00:10:46,746 --> 00:10:48,046 What am I supposed to do? 248 00:10:50,650 --> 00:10:51,883 [bleep] 249 00:10:58,624 --> 00:10:59,924 [Demetri] After rough seas 250 00:10:59,959 --> 00:11:01,292 caused the sub to collide 251 00:11:01,327 --> 00:11:03,261 with the back of the ship on launch, 252 00:11:03,295 --> 00:11:06,931 the sub has lost one of its external cameras. 253 00:11:06,999 --> 00:11:09,167 The team can't see any other damage 254 00:11:09,201 --> 00:11:11,636 and decide to press ahead with the dive. 255 00:11:11,671 --> 00:11:15,173 - [man] LF, this is SO. - [Victor] LF, go ahead. 256 00:11:15,207 --> 00:11:16,741 [man] Okay, you're clear to dive. 257 00:11:16,776 --> 00:11:17,676 Clear to dive. 258 00:11:17,710 --> 00:11:20,045 Pumping in. Okay, here we go. 259 00:11:30,623 --> 00:11:33,158 We're descending. We're underwater. 260 00:11:33,192 --> 00:11:35,393 - It's eerily quiet. - Yeah. 261 00:11:39,598 --> 00:11:41,433 [Demetri] The green color of the water here 262 00:11:41,467 --> 00:11:43,902 is evidence of what makes the Southern Ocean 263 00:11:43,936 --> 00:11:46,304 so vital to life around the world. 264 00:11:46,338 --> 00:11:48,206 Plentiful nutrients build up here 265 00:11:48,240 --> 00:11:50,075 during the long, dark winters, 266 00:11:50,109 --> 00:11:51,409 and in the summer feed 267 00:11:51,444 --> 00:11:53,578 explosions of microscopic plants 268 00:11:53,612 --> 00:11:56,147 called phytoplankton. 269 00:11:56,181 --> 00:11:58,049 They bloom in such quantities 270 00:11:58,084 --> 00:12:02,353 that NASA has even been able to track them from space. 271 00:12:02,388 --> 00:12:04,856 [Paula] It was mind-blowing that on that type of scale 272 00:12:04,890 --> 00:12:06,758 in the Southern Ocean, the phytoplankton were 273 00:12:06,792 --> 00:12:08,493 responding to the surface currents 274 00:12:08,527 --> 00:12:10,261 and the winds, and their distribution, 275 00:12:10,296 --> 00:12:12,263 and you could see that from space. 276 00:12:13,399 --> 00:12:15,433 [Demetri] Plants depend on light 277 00:12:15,468 --> 00:12:17,202 and so they live in a narrow band 278 00:12:17,236 --> 00:12:18,837 near the surface, 279 00:12:18,871 --> 00:12:21,473 the Sunlight Zone. 280 00:12:21,507 --> 00:12:23,908 And here, they in turn support an abundance 281 00:12:23,943 --> 00:12:26,511 of microorganisms called krill 282 00:12:26,545 --> 00:12:31,683 which feed a rich food chain, from penguins... 283 00:12:31,717 --> 00:12:33,318 to killer whales. 284 00:12:37,123 --> 00:12:39,991 Passing below 650 feet, 285 00:12:40,025 --> 00:12:43,428 the sub enters the Twilight Zone. 286 00:12:43,462 --> 00:12:44,896 Here, the light dwindles 287 00:12:44,930 --> 00:12:46,765 and the ocean's microscopic plants 288 00:12:46,799 --> 00:12:48,466 can no longer survive. 289 00:12:49,568 --> 00:12:52,504 Yet life does thrive here. 290 00:12:52,538 --> 00:12:55,874 Like this ice fish. Its blood still runs 291 00:12:55,908 --> 00:12:59,377 because it has a natural antifreeze in its veins. 292 00:13:02,515 --> 00:13:06,117 And transparent, jelly-like organisms called salps 293 00:13:06,152 --> 00:13:08,953 that string together in long chains. 294 00:13:11,624 --> 00:13:13,358 [Victor] See, look how dark it is. 295 00:13:13,392 --> 00:13:14,959 [Alan] That's incredible, isn't it? 296 00:13:14,994 --> 00:13:19,564 Surface, this is LF. Present depth, 348 meters. 297 00:13:20,933 --> 00:13:22,767 [Demetri] Victor and Alan have been underwater 298 00:13:22,802 --> 00:13:24,402 for just ten minutes, 299 00:13:24,436 --> 00:13:26,538 but the surface crew have spotted evidence 300 00:13:26,572 --> 00:13:28,973 of a worrying fault with the sub. 301 00:13:29,008 --> 00:13:31,876 [Alan] I think it's best to report, just in case. 302 00:13:31,911 --> 00:13:35,013 - Kelvin, Xeno. - [Kelvin] Go ahead. 303 00:13:35,047 --> 00:13:36,381 [Alan] Yeah, just for you information 304 00:13:36,415 --> 00:13:39,050 Looks like I can see a small oil slick. 305 00:13:40,719 --> 00:13:42,921 [Demetri] It seems that when one of the sub's cameras 306 00:13:42,955 --> 00:13:44,622 was damaged on launch, 307 00:13:44,657 --> 00:13:46,524 it breached the oil-filled pipes 308 00:13:46,559 --> 00:13:49,527 that carry electrical wires around the sub. 309 00:13:49,562 --> 00:13:51,262 It's now only a matter of time 310 00:13:51,297 --> 00:13:53,198 before seawater gets in 311 00:13:53,232 --> 00:13:57,035 and shorts out a vital part of the electrical system. 312 00:13:57,069 --> 00:13:59,437 The sub's power comes from six batteries 313 00:13:59,471 --> 00:14:03,575 packed into detachable pods on either side of the sphere. 314 00:14:03,609 --> 00:14:05,910 They, in turn, link to junction boxes 315 00:14:05,945 --> 00:14:08,613 that supply the sub's components. 316 00:14:08,647 --> 00:14:10,315 To protect the wires and electronics 317 00:14:10,349 --> 00:14:11,816 from the pressures of the deep, 318 00:14:11,851 --> 00:14:14,919 the boxes and pipes are all filled with oil. 319 00:14:14,954 --> 00:14:17,021 Because oil is lighter than water, 320 00:14:17,056 --> 00:14:18,556 it's now escaping from the breach 321 00:14:18,591 --> 00:14:20,124 at the top of the sub, 322 00:14:20,159 --> 00:14:22,227 letting water seep in. 323 00:14:22,261 --> 00:14:24,529 If it reaches the junction box, 324 00:14:24,563 --> 00:14:26,731 it will knock out multiple components, 325 00:14:26,765 --> 00:14:29,934 leaving Victor without full control of the sub 326 00:14:29,969 --> 00:14:33,104 2,000 feet below the surface. 327 00:14:33,138 --> 00:14:36,241 [Patrick] Okay, response. Need you to instruct 328 00:14:36,275 --> 00:14:37,942 the LF to abort the dive. 329 00:14:37,977 --> 00:14:40,044 They're gonna have to abort the dive. 330 00:14:40,079 --> 00:14:42,146 There are times when you have to call it, 331 00:14:42,181 --> 00:14:45,350 and even if it's unpopular, you do it because 332 00:14:45,384 --> 00:14:47,085 you have to do what's safe. 333 00:14:47,119 --> 00:14:49,754 [Response] LF, LF, this is the response. 334 00:14:49,788 --> 00:14:51,389 Please abort the dive. 335 00:14:51,423 --> 00:14:53,258 Abort the dive. 336 00:14:54,793 --> 00:14:56,594 Roger that. Aborting dive. 337 00:14:56,629 --> 00:14:58,863 - Repeat. Aborting dive. - Why? 338 00:14:58,898 --> 00:15:00,064 [Victor] When we lost the camera, 339 00:15:00,099 --> 00:15:01,132 it sheared the cable 340 00:15:01,166 --> 00:15:03,935 - so oil started leaking. - Oh. 341 00:15:03,969 --> 00:15:06,304 [Demetri] Victor must now make a controlled release 342 00:15:06,338 --> 00:15:09,274 of enough diving weights to bring the sub safely 343 00:15:09,308 --> 00:15:10,842 back to the surface. 344 00:15:10,876 --> 00:15:13,544 [Victor] Ejecting weights. 345 00:15:13,579 --> 00:15:17,582 All weights jettisoned. Ascending to surface. 346 00:15:17,616 --> 00:15:19,350 Get ready to brace. 347 00:15:33,933 --> 00:15:35,099 [Patrick] We had to abort you, man. 348 00:15:35,134 --> 00:15:37,201 Cause you would have... you would have lost your... 349 00:15:37,236 --> 00:15:39,037 and you would have lost your modem anyway. 350 00:15:39,071 --> 00:15:40,371 So, at some point, you'd have been coming up 351 00:15:40,406 --> 00:15:42,106 even if you didn't want to. 352 00:15:45,945 --> 00:15:48,813 [Demetri] Repairs to the damaged sub begin. 353 00:15:48,847 --> 00:15:50,248 Try to give it a little bit. 354 00:15:50,282 --> 00:15:51,683 [Demetri] And the team encounter 355 00:15:51,717 --> 00:15:53,117 another deadly hazard 356 00:15:53,152 --> 00:15:54,686 of the Southern Ocean. 357 00:15:56,455 --> 00:15:58,556 Icebergs. 358 00:15:58,590 --> 00:16:01,092 A specialist ice pilot has joined forces 359 00:16:01,126 --> 00:16:02,760 with the captain to navigate 360 00:16:02,795 --> 00:16:06,597 through these unpredictable ship sinkers. 361 00:16:06,632 --> 00:16:08,199 [Berndt] Nine tenths of an iceberg 362 00:16:08,233 --> 00:16:10,301 is underneath the ice. 363 00:16:12,004 --> 00:16:15,073 And I've seen icebergs going against the wind 364 00:16:15,107 --> 00:16:18,009 which is completely not intuitive. 365 00:16:19,445 --> 00:16:21,179 [Demetri] To begin with, the icebergs 366 00:16:21,213 --> 00:16:23,247 are relatively small. 367 00:16:23,282 --> 00:16:25,950 But then comes a monster. 368 00:16:28,053 --> 00:16:31,422 [Stuart] That's the target. It's dead ahead of us now. 369 00:16:31,457 --> 00:16:32,857 [Victor] Is this the biggest you've ever... 370 00:16:32,891 --> 00:16:34,459 I've never seen one this big. 371 00:16:34,493 --> 00:16:38,062 It's extraordinary. It goes off into the horizon. 372 00:16:38,097 --> 00:16:40,198 [Heather] And it disappears off into the fog. 373 00:16:40,232 --> 00:16:43,835 And then disappears off into the fog on the other side. 374 00:16:43,869 --> 00:16:46,738 [Victor] This is massive! How long is it, Stu? 375 00:16:46,772 --> 00:16:48,806 About 18 miles, this one, I think. 376 00:16:48,841 --> 00:16:50,675 It's more than a half marathon long. 377 00:16:52,044 --> 00:16:53,911 You know icebergs actually pose a true danger, 378 00:16:53,946 --> 00:16:55,413 so when I'm coming up from the bottom 379 00:16:55,447 --> 00:16:58,049 I don't want to be going up too fast because I don't know 380 00:16:58,083 --> 00:17:00,284 what's directly on top of me. 381 00:17:02,888 --> 00:17:04,355 [Demetri] Finally, the team arrive 382 00:17:04,390 --> 00:17:06,858 above the South Sandwich Trench, 383 00:17:06,892 --> 00:17:08,459 a vast underwater canyon 384 00:17:08,494 --> 00:17:11,763 that's a staggering 4.5 miles deep. 385 00:17:11,797 --> 00:17:14,332 Their first task is to identify on the floor 386 00:17:14,366 --> 00:17:16,467 of the trench the precise location 387 00:17:16,502 --> 00:17:19,871 of the deepest point in the Southern Ocean. 388 00:17:19,905 --> 00:17:21,305 Using one of the most powerful 389 00:17:21,340 --> 00:17:23,541 sonar scanning systems in the world, 390 00:17:23,575 --> 00:17:27,278 they begin to map, for the very first time in history, 391 00:17:27,312 --> 00:17:30,348 an extraordinary hidden landscape. 392 00:17:30,382 --> 00:17:32,617 [Victor] If this were inverted and was a mountain range, 393 00:17:32,651 --> 00:17:34,585 it would actually be higher 394 00:17:34,620 --> 00:17:36,854 than the entire Andes mountain chain. 395 00:17:36,889 --> 00:17:37,922 It's massive. 396 00:17:39,558 --> 00:17:41,325 [Demetri] The South Sandwich Trench 397 00:17:41,360 --> 00:17:44,228 is a staggering 600 miles long, 398 00:17:44,296 --> 00:17:46,664 stretching from the lower reaches of the Atlantic 399 00:17:46,698 --> 00:17:49,400 down into the Southern Ocean itself. 400 00:17:51,270 --> 00:17:52,637 But up on the bridge, 401 00:17:52,671 --> 00:17:54,672 the team spot a growing threat 402 00:17:54,706 --> 00:17:56,574 to the deep dive. 403 00:17:56,608 --> 00:17:58,743 [Victor] These storms are moving faster than expected. 404 00:17:58,777 --> 00:18:00,111 The two low-pressure systems are causing 405 00:18:00,145 --> 00:18:02,080 all this weather to go in a funnel. 406 00:18:02,114 --> 00:18:03,981 We can't outrun it. We point the ship 407 00:18:04,016 --> 00:18:06,250 into the storm and we ride it out. 408 00:18:14,026 --> 00:18:16,360 [Demetri] In the freezing waters of the Southern Ocean, 409 00:18:16,395 --> 00:18:18,996 an approaching storm is threatening to derail 410 00:18:19,031 --> 00:18:23,067 Victor's attempt to discover and dive its deepest point. 411 00:18:23,102 --> 00:18:24,335 We are in the screaming 60s. 412 00:18:24,369 --> 00:18:26,671 You do not hang out at this latitude 413 00:18:26,705 --> 00:18:28,873 and not have storms come at you. 414 00:18:28,907 --> 00:18:32,009 Even if it's rough weather, we're gonna tough it out, 415 00:18:32,044 --> 00:18:33,778 so we can get the bio samples, 416 00:18:33,812 --> 00:18:34,812 even if we don't dive it. 417 00:18:34,847 --> 00:18:36,414 I would like to deploy the landers. 418 00:18:36,448 --> 00:18:39,550 [Demetri] The landers are underwater scientific probes 419 00:18:39,585 --> 00:18:43,287 packed with sensors, cameras and traps. 420 00:18:43,322 --> 00:18:46,524 They are vital for the team's mission to explore what life 421 00:18:46,558 --> 00:18:49,527 could possibly exist in the icy waters 422 00:18:49,561 --> 00:18:52,063 24,000 feet below. 423 00:18:52,097 --> 00:18:53,364 [Paul] Pretty exciting. I mean, we are 424 00:18:53,398 --> 00:18:54,732 at the limits of this planet. 425 00:18:54,766 --> 00:18:57,034 Basically, ultra-cold and high pressure 426 00:18:57,069 --> 00:18:59,237 is very hard to adapt to. 427 00:18:59,271 --> 00:19:01,439 [Demetri] There are five landers on board, 428 00:19:01,473 --> 00:19:04,041 costing up to $200,000 each. 429 00:19:04,076 --> 00:19:06,677 But with the storm on its way, to launch and retrieve 430 00:19:06,712 --> 00:19:11,048 these near one-ton monsters could put lives on the line. 431 00:19:11,083 --> 00:19:13,251 [Alan] Hope it doesn't storm more. We don't want 432 00:19:13,285 --> 00:19:14,552 ice forming on the deck. 433 00:19:14,586 --> 00:19:15,820 If any one of us fell in the water, 434 00:19:15,854 --> 00:19:17,255 I mean because it's so cold down here, 435 00:19:17,289 --> 00:19:19,590 you get hypothermia pretty fast. 436 00:19:19,625 --> 00:19:20,758 [Heather] Watch out. 437 00:19:23,295 --> 00:19:25,263 [Alan D] Come down the wire. 438 00:19:25,297 --> 00:19:27,498 [Alan J] It's going that way. 439 00:19:27,533 --> 00:19:29,734 Okay, tags off. 440 00:19:29,768 --> 00:19:31,135 [Heather] Lovely job. 441 00:19:32,437 --> 00:19:34,205 [Demetri] Despite the conditions, 442 00:19:34,239 --> 00:19:37,542 two science probes are heading for the seabed. 443 00:19:39,545 --> 00:19:42,446 Eight hours later, and after a remote release, 444 00:19:42,481 --> 00:19:44,482 they are due back on the surface. 445 00:19:44,516 --> 00:19:47,418 But now the weather is taking a dramatic turn 446 00:19:47,452 --> 00:19:49,287 for the worse. 447 00:19:49,321 --> 00:19:52,089 [Alan] The nature of what we do is notoriously dangerous 448 00:19:52,124 --> 00:19:55,326 in terms of equipment-wise and weather-wise. 449 00:19:55,360 --> 00:19:56,661 You psychologically prepare yourself 450 00:19:56,695 --> 00:19:58,329 because with all best intentions 451 00:19:58,363 --> 00:19:59,897 you can plan an expedition for two years 452 00:19:59,932 --> 00:20:03,201 and you go there and it just goes wrong. 453 00:20:03,235 --> 00:20:04,335 [man] Where are they? 454 00:20:05,971 --> 00:20:07,471 [Stuart] I've got it. Okay Xeno, 455 00:20:07,506 --> 00:20:10,308 we have a visual about 800 meters west of us. 456 00:20:10,342 --> 00:20:11,609 [man] Roger that. 457 00:20:16,882 --> 00:20:18,249 [Victor] Oh, man. 458 00:20:22,821 --> 00:20:24,522 [Alan] Just watch that arm, it's just... 459 00:20:24,556 --> 00:20:26,390 if it takes one little roll... 460 00:20:30,929 --> 00:20:32,530 [Victor] It's scary. 461 00:20:32,564 --> 00:20:35,399 [Alan D] Line come down, right. 462 00:20:37,369 --> 00:20:38,636 [man] Going up! 463 00:20:40,739 --> 00:20:43,808 [Alan D] Down, down, down, Down on the wire. 464 00:20:43,842 --> 00:20:44,909 [man yelling] 465 00:20:47,346 --> 00:20:49,747 [Paul] Where is it? 466 00:20:49,781 --> 00:20:51,082 It hasn't worked, no. 467 00:20:55,120 --> 00:20:56,254 [man] We have lost it. 468 00:20:57,456 --> 00:21:00,291 See what happened to the rope? 469 00:21:00,325 --> 00:21:01,926 Looks like something chewed it, 470 00:21:05,464 --> 00:21:07,732 [Demetri] A crucial piece of scientific equipment 471 00:21:07,766 --> 00:21:10,334 and any extreme lifeforms it may have captured 472 00:21:10,369 --> 00:21:12,737 are now plummeting back to the seabed, 473 00:21:12,771 --> 00:21:14,538 never to be seen again. 474 00:21:16,608 --> 00:21:19,310 And now comes more bad news. 475 00:21:19,344 --> 00:21:22,980 The crew have failed to locate the second probe. 476 00:21:23,015 --> 00:21:24,415 [Alan] We should be seeing that strobe 477 00:21:24,449 --> 00:21:26,517 clear as day by now, right? 478 00:21:26,551 --> 00:21:28,352 [Demetri] And because the Antarctic winter 479 00:21:28,387 --> 00:21:30,288 is now fast approaching, 480 00:21:30,322 --> 00:21:33,524 they must abandon the search and move on. 481 00:21:34,893 --> 00:21:37,795 [Paul] Very distressing, yeah we have limited time 482 00:21:37,829 --> 00:21:39,163 and we've got bad weather coming 483 00:21:39,197 --> 00:21:41,065 and we might not get another chance 484 00:21:46,104 --> 00:21:48,439 [Demetri] There is better news for the sonar team 485 00:21:48,473 --> 00:21:49,807 mapping the trench. 486 00:21:49,841 --> 00:21:51,242 Wow. what is that? 487 00:21:51,276 --> 00:21:54,111 [Cassie] This is a sea mound that's 1100 meters 488 00:21:54,146 --> 00:21:55,680 off the sea floor. 489 00:21:57,516 --> 00:22:01,118 [Demetri] The sea mound is an extinct underwater volcano. 490 00:22:01,153 --> 00:22:04,755 Previously unknown, the team get to name it. 491 00:22:04,790 --> 00:22:06,691 It's a stark reminder that we know more 492 00:22:06,725 --> 00:22:08,459 about the surface of the moon 493 00:22:08,493 --> 00:22:10,428 than the seabed of our own planet. 494 00:22:10,462 --> 00:22:12,263 It's just fantastic. I mean, nobody knew 495 00:22:12,297 --> 00:22:14,198 anything about this area. 496 00:22:14,232 --> 00:22:16,300 And look at all the amazing features 497 00:22:16,335 --> 00:22:19,537 that have been imaged by the sonar. 498 00:22:19,571 --> 00:22:22,073 [Demetri] The new data also bolsters the theory 499 00:22:22,107 --> 00:22:24,475 that the South Sandwich Trench is the root 500 00:22:24,509 --> 00:22:26,477 of the mysterious lifeblood current 501 00:22:26,511 --> 00:22:29,113 which feeds the world. 502 00:22:29,147 --> 00:22:31,615 [Oscar] When you carve trenches in the ocean, 503 00:22:31,650 --> 00:22:34,352 you create a funnel where water flows. 504 00:22:34,386 --> 00:22:38,055 Are these trenches reservoirs relatively undisturbed? 505 00:22:38,090 --> 00:22:40,958 Or are they dynamic through-flows of water? 506 00:22:41,993 --> 00:22:43,561 [Demetri] To confirm the theory, 507 00:22:43,595 --> 00:22:47,331 the team need to sample the deep trench itself. 508 00:22:47,366 --> 00:22:49,400 And now, for the first time in history, 509 00:22:49,434 --> 00:22:52,470 they've accurately pinpointed the very deepest site 510 00:22:52,504 --> 00:22:54,038 in the Southern Ocean. 511 00:22:54,072 --> 00:22:55,339 [Cassie] Based on the satellite data, 512 00:22:55,374 --> 00:22:57,141 this one right here has always been the one 513 00:22:57,175 --> 00:23:00,044 that we thought was going to be the deepest, 514 00:23:00,078 --> 00:23:01,779 or this last one. 515 00:23:01,813 --> 00:23:04,348 No one considered a third one. 516 00:23:04,383 --> 00:23:08,285 Now we know the deepest point in the Southern Ocean 517 00:23:08,320 --> 00:23:10,020 is this yellow dot right here. 518 00:23:10,055 --> 00:23:10,921 [Victor] Wow. 519 00:23:12,824 --> 00:23:17,962 [Demetri] A staggering 24,388 feet below the surface. 520 00:23:17,996 --> 00:23:20,197 This is Victor's target for a dive 521 00:23:20,232 --> 00:23:23,167 he's determined to take on alone. 522 00:23:23,201 --> 00:23:24,735 [Victor] Doing things solo, 523 00:23:24,770 --> 00:23:27,204 you're completely responsible for everything that happens. 524 00:23:27,239 --> 00:23:28,339 And you're doing it by yourself 525 00:23:28,373 --> 00:23:30,541 with such intense focus. 526 00:23:30,575 --> 00:23:32,109 It makes it more interesting. I guess for me. 527 00:23:32,144 --> 00:23:34,545 It's more exciting. You're completely on your own. 528 00:23:36,715 --> 00:23:38,582 [Demetri] There are now just days left 529 00:23:38,617 --> 00:23:40,451 before the Antarctic summer ends 530 00:23:40,485 --> 00:23:42,720 and the Southern Ocean becomes too dangerous 531 00:23:42,754 --> 00:23:44,054 to dive. 532 00:23:44,089 --> 00:23:46,791 With rough seas forecast for tomorrow, 533 00:23:46,825 --> 00:23:48,926 it's now or never. 534 00:23:48,960 --> 00:23:52,596 But there are major concerns for Victor's safety. 535 00:23:56,067 --> 00:23:58,102 I don't wanna slam into the bottom of an iceberg. 536 00:23:58,136 --> 00:24:00,871 There are huge bricks of ice out there. 537 00:24:00,906 --> 00:24:02,940 Apartment-sized blocks of ice. 538 00:24:14,853 --> 00:24:17,588 [Demetri] The expedition team are facing a major setback 539 00:24:17,622 --> 00:24:19,723 in their plans to send Victor down 540 00:24:19,758 --> 00:24:22,593 to the deepest point of the Southern Ocean. 541 00:24:22,627 --> 00:24:27,164 Icebergs that could threaten his return to the surface. 542 00:24:27,199 --> 00:24:30,501 Despite the risks, they decide to press ahead. 543 00:24:30,535 --> 00:24:32,036 He's gonna make a very careful and deliberate 544 00:24:32,070 --> 00:24:33,237 return to the surface. 545 00:24:33,271 --> 00:24:36,474 We want to make sure that he verifies himself 546 00:24:36,508 --> 00:24:38,742 with cameras that the surface is clear. 547 00:24:38,777 --> 00:24:42,046 Just in case we have him misplaced on our chart. 548 00:24:42,080 --> 00:24:44,815 Frankly, I'm gonna use light power to slowly go up. 549 00:24:44,850 --> 00:24:48,285 I'm not gonna drop the freeboard to rocket up. 550 00:24:48,320 --> 00:24:49,954 [Demetri] The team prepare to launch Victor 551 00:24:49,988 --> 00:24:51,555 on his historic attempt 552 00:24:51,590 --> 00:24:52,890 into the freezing temperatures 553 00:24:52,924 --> 00:24:56,093 of the deep trench beyond any hope of rescue. 554 00:24:56,161 --> 00:24:57,361 Okay. You're going to have a great dive. 555 00:24:57,395 --> 00:24:58,762 I know. It'll be awesome. 556 00:24:58,797 --> 00:25:00,598 [Glenn] Going to the bottom of the ocean in a submersible 557 00:25:00,632 --> 00:25:02,466 is like going on a space mission 558 00:25:02,501 --> 00:25:05,169 in terms of the isolation. 559 00:25:05,203 --> 00:25:07,838 - [Kelvin] Coming down! - Hatch coming down. Thank you. 560 00:25:07,873 --> 00:25:09,039 Okay, let's do this. 561 00:25:09,074 --> 00:25:10,307 Get him in, boys. 562 00:25:10,342 --> 00:25:13,477 [Glenn] The cold, extreme remoteness 563 00:25:13,512 --> 00:25:14,645 will play on Victor's mind 564 00:25:14,679 --> 00:25:16,680 because if anything goes wrong, 565 00:25:16,715 --> 00:25:18,482 you're right at the end 566 00:25:18,517 --> 00:25:21,352 of the most stretched rubber band in history. 567 00:25:21,386 --> 00:25:24,221 And you're really hoping that we'll pull you back. 568 00:25:26,825 --> 00:25:29,126 [Victor] LF, It's pumping in. 569 00:25:29,160 --> 00:25:30,594 Proceeding to dive. 570 00:25:30,629 --> 00:25:32,129 [indistinct radio chatter] 571 00:25:35,066 --> 00:25:37,868 Roger that, I'll try thrusters down. Thanks. 572 00:25:41,573 --> 00:25:43,173 And down we go! 573 00:25:53,451 --> 00:25:54,652 Looking outside the portal, 574 00:25:54,686 --> 00:25:56,987 looks like a lot of food down here. 575 00:25:57,022 --> 00:26:00,324 Oh, I just saw a jellyfish. 576 00:26:00,358 --> 00:26:03,093 Surface, LF. Present depth. 577 00:26:03,128 --> 00:26:05,896 [man] Present depth, 487. 578 00:26:05,931 --> 00:26:08,666 - Light support good. - Roger that, LF. 579 00:26:08,700 --> 00:26:12,036 We have you loud and clear. Well, that was quick. 580 00:26:12,070 --> 00:26:13,604 Whoo! [laughs] 581 00:26:13,638 --> 00:26:16,607 I mean he is whistling down! 582 00:26:16,641 --> 00:26:17,975 [Demetri] Within just minutes, 583 00:26:18,009 --> 00:26:20,210 Victor reaches the very deepest zones 584 00:26:20,245 --> 00:26:21,579 of the Southern Ocean. 585 00:26:21,613 --> 00:26:23,213 The Midnight Zone. 586 00:26:23,248 --> 00:26:25,549 Where no light at all can penetrate. 587 00:26:25,584 --> 00:26:27,217 And where extraordinary creatures 588 00:26:27,252 --> 00:26:30,187 are still being discovered. 589 00:26:30,221 --> 00:26:32,623 The giant sea spider whose internal organs 590 00:26:32,657 --> 00:26:35,159 are carried inside its legs. 591 00:26:37,329 --> 00:26:40,230 The feather star, which uses the long spines 592 00:26:40,265 --> 00:26:43,400 along its arms to filter out microscopic food 593 00:26:43,435 --> 00:26:45,269 from the water. 594 00:26:45,303 --> 00:26:49,006 And visitors from above. Deep-diving sperm whales 595 00:26:49,040 --> 00:26:51,342 which have the largest brains of any creature 596 00:26:51,376 --> 00:26:53,711 that's ever lived on Earth. 597 00:26:56,748 --> 00:26:58,349 At 13,000 feet, 598 00:26:58,383 --> 00:27:01,852 Victor enters the Abyssal Zone. 599 00:27:01,886 --> 00:27:05,322 Home to sea pigs that inflate up to seven pairs of legs 600 00:27:05,357 --> 00:27:09,360 to walk around the sea floor. 601 00:27:09,394 --> 00:27:12,129 And alarm jellyfish that if attacked 602 00:27:12,163 --> 00:27:14,331 emit bioluminescent flashes 603 00:27:14,366 --> 00:27:16,300 thought to act like a burglar alarm 604 00:27:16,334 --> 00:27:19,837 to attract bigger predators to the scene. 605 00:27:19,871 --> 00:27:21,705 Can already feel the cold coming through the bottom 606 00:27:21,740 --> 00:27:23,807 of the submersible. 607 00:27:23,842 --> 00:27:26,210 [Demetri] The temperature of the saltwater outside 608 00:27:26,244 --> 00:27:28,245 has now dipped below freezing. 609 00:27:39,591 --> 00:27:41,692 I'm checking to see if I hear something unusual. 610 00:27:41,726 --> 00:27:45,396 I don't have any systems on. I'm not using thrusters. 611 00:27:45,430 --> 00:27:47,831 It's almost like a hum. 612 00:27:47,866 --> 00:27:50,901 It does sound like a low hum 613 00:27:50,935 --> 00:27:52,102 coming from outside the sub. 614 00:27:52,137 --> 00:27:54,104 I don't think I've heard that before. 615 00:27:56,174 --> 00:27:58,442 There's so much background noise right now. 616 00:27:58,476 --> 00:27:59,810 Seems to be coming from the submarine, 617 00:27:59,844 --> 00:28:01,812 you can't hear the surface. 618 00:28:01,846 --> 00:28:03,147 Surface, LF. 619 00:28:03,181 --> 00:28:06,517 Present depth, five-zero-three-one. 620 00:28:06,551 --> 00:28:08,452 I cannot read you. 621 00:28:08,486 --> 00:28:11,755 - I cannot read you. - LF, 622 00:28:11,790 --> 00:28:15,826 comms check. Comms check. 623 00:28:18,096 --> 00:28:20,531 He didn't hear me. He didn't acknowledge. 624 00:28:24,069 --> 00:28:26,036 [bleep] what's going on with that thing? 625 00:28:26,071 --> 00:28:28,839 Do you read me? Do you read me at all? 626 00:28:30,742 --> 00:28:33,444 [Kelvin] As a submarine pilot, you don't want to lose 627 00:28:33,478 --> 00:28:35,045 communication with the surface. 628 00:28:35,080 --> 00:28:37,948 That's extremely dangerous. Extremely dangerous. 629 00:28:41,686 --> 00:28:43,754 Status! Status! 630 00:28:45,857 --> 00:28:48,325 What the [bleep] going on where he can't hear us? 631 00:28:59,170 --> 00:29:01,505 [Victor] Surface, surface. 632 00:29:01,539 --> 00:29:03,040 How do you read? 633 00:29:03,074 --> 00:29:05,843 Loud and clear. Loud and clear. 634 00:29:07,912 --> 00:29:12,282 Crystal clear audio. I can hear him. 635 00:29:13,718 --> 00:29:15,886 [Demetri] It's a critical moment in the dive. 636 00:29:15,920 --> 00:29:20,557 Should Victor abandon or continue into the deep? 637 00:29:20,592 --> 00:29:22,960 [sighs] Maybe it's the cold water or something. 638 00:29:22,994 --> 00:29:25,462 3,000 meters from the... from the bottom. 639 00:29:25,497 --> 00:29:26,663 I may just keep going. 640 00:29:28,233 --> 00:29:30,367 I've come all this way. 641 00:29:30,401 --> 00:29:31,869 We're gonna achieve the mission here. 642 00:29:33,071 --> 00:29:35,572 I'm not gonna abort for comms out. 643 00:29:37,442 --> 00:29:40,210 [Demetri] As he descends further into the trench, 644 00:29:40,245 --> 00:29:42,112 it's not just the communications system 645 00:29:42,147 --> 00:29:43,580 under attack from the freezing 646 00:29:43,615 --> 00:29:44,848 Antarctic waters. 647 00:29:50,922 --> 00:29:53,690 The electrical supply to the external cameras 648 00:29:53,725 --> 00:29:56,393 has also cut out. 649 00:29:56,427 --> 00:29:58,228 Well, now I'm really alone. 650 00:29:58,263 --> 00:29:59,830 I don't have comms to the surface, 651 00:29:59,864 --> 00:30:01,899 I'm in a submersible by myself, 652 00:30:01,933 --> 00:30:04,401 going down to the bottom of the Southern Ocean. 653 00:30:04,435 --> 00:30:06,603 [rapid beeping] 654 00:30:18,049 --> 00:30:20,984 [Demetri] In Mission Control, it's been two hours 655 00:30:21,019 --> 00:30:24,755 since they last made contact with the sub. 656 00:30:26,891 --> 00:30:28,225 Attention all stations. 657 00:30:28,259 --> 00:30:31,662 Be advised that we can hear Victor 658 00:30:31,696 --> 00:30:33,831 but we cannot communicate with him. 659 00:30:33,865 --> 00:30:35,065 He cannot hear us. 660 00:30:35,133 --> 00:30:36,333 He's very close to the lander. 661 00:30:36,367 --> 00:30:37,901 [man] I'd say within a couple of hundred meters, 662 00:30:37,936 --> 00:30:40,704 so he must be near the bottom. 663 00:30:42,207 --> 00:30:43,807 Insulation fault. That's probably 664 00:30:43,842 --> 00:30:45,876 just some water residue in there. 665 00:30:45,910 --> 00:30:48,011 Everything's looking good. 666 00:30:48,046 --> 00:30:50,280 I should be getting really close now. 667 00:30:50,315 --> 00:30:52,449 Oh, my. 668 00:30:52,483 --> 00:30:55,118 I can see something on the bottom. 669 00:30:55,153 --> 00:30:58,488 I'm seeing the bottom much more clearly. 670 00:31:06,731 --> 00:31:09,333 I've just reached the bottom of the Southern Ocean. 671 00:31:09,367 --> 00:31:12,369 Looks like a moonscape out of one of my portholes. 672 00:31:12,403 --> 00:31:16,506 Surface, LF. At bottom. Repeat. At bottom. 673 00:31:16,541 --> 00:31:19,509 - On the bottom. - [cheering] 674 00:31:19,544 --> 00:31:21,979 [clapping] 675 00:31:23,181 --> 00:31:26,149 I am at bottom. 676 00:31:26,184 --> 00:31:29,286 I'm at the bottom of the Southern Ocean. 677 00:31:29,320 --> 00:31:33,590 [Demetri] Victor is an amazing 24,388 feet 678 00:31:33,625 --> 00:31:35,292 below the surface. 679 00:31:35,326 --> 00:31:38,495 Where no human has ever been before. 680 00:31:42,533 --> 00:31:44,301 The team have also deployed here 681 00:31:44,335 --> 00:31:46,436 their three remaining science probes, 682 00:31:46,471 --> 00:31:51,108 or landers, baited with tempting fish carcasses. 683 00:31:51,142 --> 00:31:53,243 And although Victor's external sub cameras 684 00:31:53,278 --> 00:31:54,444 may have cut out, 685 00:31:54,479 --> 00:31:55,913 amazingly, the cameras 686 00:31:55,947 --> 00:31:58,882 on the landers are still working. 687 00:31:58,917 --> 00:32:02,753 They now capture Victor's arrival at the bottom. 688 00:32:02,787 --> 00:32:08,125 His lights just visible across the sea floor. 689 00:32:08,159 --> 00:32:10,560 These are the first ever images captured 690 00:32:10,595 --> 00:32:13,931 at the bottom of the South Sandwich Trench. 691 00:32:13,965 --> 00:32:15,999 And attracted by the lander's bait, 692 00:32:16,034 --> 00:32:19,069 there's already a crowd of super-strange specialists 693 00:32:19,103 --> 00:32:23,407 able to endure intense cold and enormous pressure. 694 00:32:23,441 --> 00:32:26,276 [Victor] See tiny white... they're like perfectly white. 695 00:32:26,311 --> 00:32:29,146 They look like tadpoles. 696 00:32:29,180 --> 00:32:32,182 What's that over there? A larger creature. 697 00:32:32,216 --> 00:32:35,152 A little pink on the... on the top. 698 00:32:35,186 --> 00:32:39,389 It has a little pink head. Two big eyes. 699 00:32:39,424 --> 00:32:41,124 Oh, he's definitely swimming. 700 00:32:41,159 --> 00:32:43,727 He's swimming away from my blast. 701 00:32:43,761 --> 00:32:47,030 [Demetri] It seems that Victor has identified a mysid, 702 00:32:47,065 --> 00:32:49,399 a type of crustacean whose bright red color 703 00:32:49,434 --> 00:32:51,568 in fact makes it even more invisible 704 00:32:51,602 --> 00:32:55,072 in the pitch dark of the deep ocean. 705 00:32:55,106 --> 00:32:57,774 1500 feet further up the trench slope, 706 00:32:57,809 --> 00:33:00,644 a second lander is capturing remarkable images 707 00:33:00,678 --> 00:33:04,047 of the range of life that thrives here. 708 00:33:04,082 --> 00:33:08,485 Sea lilies, and tall, tubular glass sponges. 709 00:33:08,519 --> 00:33:11,154 Both snag passing microorganisms 710 00:33:11,189 --> 00:33:13,757 drifting past in the current. 711 00:33:13,791 --> 00:33:15,726 And higher up the slope still, 712 00:33:15,760 --> 00:33:18,628 a third lander is capturing the first ever footage 713 00:33:18,663 --> 00:33:23,000 in this trench of a truly remarkable creature. 714 00:33:23,034 --> 00:33:24,835 Known as a snail fish, 715 00:33:24,869 --> 00:33:29,539 this is the deepest-living kind of fish yet discovered. 716 00:33:32,744 --> 00:33:34,856 And here are two new species 717 00:33:34,880 --> 00:33:38,682 filmed for the very first time. 718 00:33:38,716 --> 00:33:41,585 The snail fish are not here for the bait itself, 719 00:33:41,619 --> 00:33:43,120 but to pick off any scavengers 720 00:33:43,154 --> 00:33:45,055 the bait attracts. 721 00:33:45,089 --> 00:33:46,289 Finally, the landers' 722 00:33:46,324 --> 00:33:48,525 auto-release mechanisms activate, 723 00:33:48,559 --> 00:33:51,495 and they head back to the surface. 724 00:33:55,166 --> 00:33:57,401 But now comes the massive challenge 725 00:33:57,435 --> 00:33:58,735 of safely retrieving 726 00:33:58,770 --> 00:34:01,571 these 200,000-dollar pieces of equipment 727 00:34:01,606 --> 00:34:03,140 in heavy seas. 728 00:34:03,174 --> 00:34:04,674 - What do we got? - [woman] I think I'll just 729 00:34:04,709 --> 00:34:05,876 be happy if it lands on deck. 730 00:34:05,910 --> 00:34:07,177 Oh, [bleep]. 731 00:34:07,211 --> 00:34:08,779 The most difficult side to catch it on, 732 00:34:08,813 --> 00:34:10,013 because of the arm. 733 00:34:10,048 --> 00:34:12,215 [Demetri] Having lost two landers already, 734 00:34:12,250 --> 00:34:14,017 the pressure is on. 735 00:34:14,052 --> 00:34:16,186 [man] Charlie, we're gonna have to cross the tag lines. 736 00:34:16,220 --> 00:34:17,587 [woman] Yeah. 737 00:34:17,622 --> 00:34:19,523 Oh. Don't lose your balance. 738 00:34:19,557 --> 00:34:21,191 [man] Oh, this thing is a nightmare. 739 00:34:21,225 --> 00:34:24,361 Whoa. Got it. Got it. Wait, wait, wait. 740 00:34:27,231 --> 00:34:31,034 - [man] All right, got it. - [woman] Good. 741 00:34:31,069 --> 00:34:34,337 Right, what does the bait look like? 742 00:34:37,708 --> 00:34:39,676 Oh, here we go. 743 00:34:39,710 --> 00:34:43,146 [Alan] It's absolutely freezing. 744 00:34:43,181 --> 00:34:45,649 [Demetri] The team have a vital hoard of specimens 745 00:34:45,683 --> 00:34:47,951 from 24,000 feet down 746 00:34:47,985 --> 00:34:50,287 whose chemical secrets could set the stage 747 00:34:50,321 --> 00:34:52,956 for scientific breakthroughs in the future. 748 00:34:52,990 --> 00:34:55,125 [Paul] Hopefully, we'll discover new molecules 749 00:34:55,159 --> 00:34:58,295 that have to do with combination of pressure 750 00:34:58,329 --> 00:35:00,764 and ultra-cold temperatures. 751 00:35:00,832 --> 00:35:03,467 Those may have all kinds of applications. 752 00:35:03,501 --> 00:35:05,435 In China, they've been able to use the osmolyte 753 00:35:05,470 --> 00:35:07,571 that we discovered in deep-sea animals 754 00:35:07,605 --> 00:35:09,906 to actually cure glaucoma, 755 00:35:09,941 --> 00:35:14,177 which is a high-pressure disease of the human eye. 756 00:35:14,212 --> 00:35:15,445 [Demetri] Sensors on the landers 757 00:35:15,480 --> 00:35:17,581 have also brought back vital information 758 00:35:17,615 --> 00:35:20,217 that could confirm the root of the lifeblood current 759 00:35:20,251 --> 00:35:22,352 carrying nutrients from the Southern Ocean 760 00:35:22,386 --> 00:35:24,287 to the rest of the world. 761 00:35:24,322 --> 00:35:27,257 The data is dispatched to the British Antarctic Survey 762 00:35:27,291 --> 00:35:29,392 in the UK, where a team have been tracking 763 00:35:29,427 --> 00:35:31,661 the current at shallower depths. 764 00:35:31,696 --> 00:35:33,864 [Hugh] The data we were very kindly given 765 00:35:33,898 --> 00:35:35,732 confirm that this is Antarctic bottom water 766 00:35:35,766 --> 00:35:38,368 and that it is going through this trench. 767 00:35:38,402 --> 00:35:41,938 The actual flow through it is tens of times the flow 768 00:35:41,973 --> 00:35:44,774 of the Amazon. Millions of tons a second. 769 00:35:44,809 --> 00:35:46,443 [Demetri] It's a breakthrough that will be vital 770 00:35:46,477 --> 00:35:48,512 for future scientific work. 771 00:35:48,546 --> 00:35:50,280 [Hugh] We can measure the waters flowing through 772 00:35:50,314 --> 00:35:52,182 to see any change, see any signals 773 00:35:52,216 --> 00:35:54,117 that are happening before it spreads out 774 00:35:54,152 --> 00:35:56,586 across the whole of the world's ocean floor. 775 00:35:56,621 --> 00:35:58,021 These very deep data 776 00:35:58,055 --> 00:36:01,458 are gonna be very valuable for a long time. 777 00:36:01,492 --> 00:36:03,760 Okay. I think that's a wrap. 778 00:36:03,794 --> 00:36:05,695 Surfacing light release. 779 00:36:05,730 --> 00:36:08,732 And we're heading up. 780 00:36:15,973 --> 00:36:18,441 [Demetri] Two and a half hours after leaving the bottom, 781 00:36:18,476 --> 00:36:21,077 Victor is now approaching the surface. 782 00:36:21,112 --> 00:36:22,712 But after his radio and cameras 783 00:36:22,780 --> 00:36:23,980 cut out in the cold, 784 00:36:24,015 --> 00:36:25,749 he has no way of knowing 785 00:36:25,783 --> 00:36:28,318 if there's an iceberg in his path. 786 00:36:28,352 --> 00:36:30,987 If there is, the sub could be pinned 787 00:36:31,022 --> 00:36:34,524 beneath the ice with no way out. 788 00:36:52,643 --> 00:36:55,445 I'm just gonna come up slow. 789 00:36:55,479 --> 00:36:57,280 Hope I don't hit an iceberg. 790 00:36:57,315 --> 00:37:00,550 If I hear a thump, I'm stopping quick. 791 00:37:00,585 --> 00:37:04,120 Going up. Just be patient, Victor. 792 00:37:04,155 --> 00:37:06,656 100 meters to go. 793 00:37:06,691 --> 00:37:10,160 [man] LF, comms check. How do you read? 794 00:37:10,194 --> 00:37:12,495 [man] Yeah. Do you have visual? 795 00:37:12,530 --> 00:37:14,364 Hang on. 796 00:37:31,682 --> 00:37:35,218 [Victor] On surface. Repeat. On surface. 797 00:37:35,253 --> 00:37:38,221 - [man] Yeah, we can see you. - I see him now, I see a light. 798 00:37:46,964 --> 00:37:48,365 [man] Welcome back, Victor. 799 00:37:48,399 --> 00:37:50,300 Thank you, gentlemen. It's good to be back. 800 00:37:50,334 --> 00:37:51,368 [man] Xeno is inbound, 801 00:37:51,402 --> 00:37:53,336 should be there in any minute. 802 00:37:53,371 --> 00:37:54,904 [Victor] Roger that. Xeno inbound. 803 00:37:54,939 --> 00:37:56,172 [man] We had some comm issues, 804 00:37:56,207 --> 00:37:58,041 but we're gonna talk about that after. 805 00:37:58,075 --> 00:38:00,644 Just glad to have you back on the surface 806 00:38:00,678 --> 00:38:03,446 and just rigging for recovery. 807 00:38:03,481 --> 00:38:05,115 Roger that. Comms were a problem, 808 00:38:05,149 --> 00:38:07,317 but the mission was a success. 809 00:38:07,351 --> 00:38:09,786 [man] Indeed it was. Indeed it was, sir. 810 00:38:09,820 --> 00:38:11,921 - Great job. - [Victor] Thank you, sir. 811 00:38:11,956 --> 00:38:14,658 [man] Just Nice and slow. Nice and slow. 812 00:38:14,692 --> 00:38:17,594 [Demetri] The sub may be safely back on the surface, 813 00:38:17,628 --> 00:38:19,829 but there's a final challenge to overcome 814 00:38:19,864 --> 00:38:22,365 in the volatile waters of the Southern Ocean. 815 00:38:22,433 --> 00:38:24,768 - [man] Ride that thing, Steve. - [Steve] Okay. 816 00:38:26,003 --> 00:38:27,804 Oh, that was a big wave, guys. 817 00:38:27,838 --> 00:38:30,785 [Steve] The LF does not like being on the surface. 818 00:38:30,809 --> 00:38:32,776 It's designed to just dive. 819 00:38:32,810 --> 00:38:35,078 Get to the bottom, get there quickly. 820 00:38:35,112 --> 00:38:36,680 And she's like a wild horse, 821 00:38:36,714 --> 00:38:38,048 like you can try to put a rope on it 822 00:38:38,082 --> 00:38:40,016 and it just fights you, right? 823 00:38:44,522 --> 00:38:45,622 Up on the main. 824 00:38:49,293 --> 00:38:54,097 - Get it, Steve. - [man] Get down on the main. 825 00:38:54,131 --> 00:38:56,199 Come on, Steve. Get... Go, go, go. 826 00:38:56,233 --> 00:38:57,667 - Go! - Come one, Steve. 827 00:38:57,702 --> 00:38:59,169 [man] Two hands, man. 828 00:38:59,203 --> 00:39:01,271 Up on the main. Up on the main. 829 00:39:03,107 --> 00:39:05,108 That's good. That's good, Patrick. 830 00:39:16,854 --> 00:39:18,688 Good job, buddy. 831 00:39:18,723 --> 00:39:20,323 Okay. 832 00:39:20,358 --> 00:39:22,125 How you doing, Steve? You wanna get off there? 833 00:39:22,159 --> 00:39:23,893 I can jump in there and do this. 834 00:39:23,928 --> 00:39:26,796 Steve, let's get you off. No, he's too cold. 835 00:39:38,008 --> 00:39:40,343 Hang in there, buddy. 836 00:39:42,346 --> 00:39:44,080 Steve, let's get you off. 837 00:39:44,115 --> 00:39:46,616 [Demetri] To prevent the onset of hypothermia, 838 00:39:46,650 --> 00:39:48,418 the expedition doctor must bring 839 00:39:48,452 --> 00:39:50,820 Steve's body temperature back up. 840 00:39:50,855 --> 00:39:52,922 He's sat him down next to the heating duct 841 00:39:52,957 --> 00:39:55,592 in the sub's hangar. 842 00:39:55,626 --> 00:39:59,095 Finally, Steve's warm enough to be moved inside. 843 00:39:59,130 --> 00:40:01,965 [indistinct chatter] 844 00:40:01,999 --> 00:40:05,635 Yeah, they're the right color. 845 00:40:05,669 --> 00:40:08,071 Keep using your hands. Good work, man. 846 00:40:08,105 --> 00:40:09,639 - Thank you. - Good work. 847 00:40:09,673 --> 00:40:11,441 [Steve] I've lived on the Tropic of Capricorn 848 00:40:11,475 --> 00:40:12,942 my whole life, 849 00:40:12,977 --> 00:40:14,344 that's close to the Equator, 850 00:40:14,378 --> 00:40:17,414 I don't do cold water. [chuckles] 851 00:40:28,025 --> 00:40:30,059 - [man speaks indistinctly] - [man] Welcome back, Victor. 852 00:40:30,094 --> 00:40:31,461 [Victor] Thank you. Good to be back. 853 00:40:31,495 --> 00:40:34,664 [cheering and whistling] 854 00:40:34,698 --> 00:40:37,233 Good job, team! 855 00:40:37,268 --> 00:40:40,937 [Demetri] At last, Victor is safely back on board. 856 00:40:40,971 --> 00:40:43,206 He's now the only person to have reached 857 00:40:43,240 --> 00:40:45,742 the deepest point of the Southern Ocean. 858 00:40:45,776 --> 00:40:50,079 The second of his five deeps. 859 00:40:50,114 --> 00:40:54,250 - Good to be back. - It's good to have you back. 860 00:40:54,285 --> 00:40:55,752 [Victor] Some interesting moments, 861 00:40:55,786 --> 00:40:56,853 feeling quite alone 862 00:40:56,887 --> 00:40:58,121 in the middle of the Southern Ocean, 863 00:40:58,155 --> 00:41:01,591 but we got it done, it's good to be back. 864 00:41:01,625 --> 00:41:04,327 All right. It's kinda cold. 865 00:41:04,361 --> 00:41:06,529 [laughs] 866 00:41:06,564 --> 00:41:09,432 Ha-ha! Thanks for getting me back. 867 00:41:10,668 --> 00:41:12,302 It's a very high-tech machine that we took 868 00:41:12,336 --> 00:41:14,704 to a very inhospitable place. 869 00:41:14,738 --> 00:41:17,240 And it was extraordinary. 870 00:41:17,274 --> 00:41:19,642 We're doing it because we're explorers. 871 00:41:19,677 --> 00:41:22,479 Because we want to see. 872 00:41:22,513 --> 00:41:23,947 We want to push the boundaries. 873 00:41:23,981 --> 00:41:24,948 We want to learn things 874 00:41:24,982 --> 00:41:26,649 that haven't been learned before. 875 00:41:26,684 --> 00:41:28,585 And we want to do it together and bring it back 876 00:41:28,619 --> 00:41:30,019 and share it with other people. 877 00:41:30,054 --> 00:41:33,056 [mellow music playing]