From the roughest seas to the crystal clear waters of the Florida springs, David Attenborough swims with sea otters and dives with manatees, as he follows those mammals who, millions of years ago, left dry land and returned to the water to feed.
Sri Lanka, the tropical island lying off the southern coast of India, is home to its own special elephants. A subspecies of the Asian elephant, they have their own unique characteristics. In this programme, award-winning wildlife cameraman Martyn Colbeck of Echo of the Elephants fame travels to Sri Lanka to try and get to know them. Martyn has planned his arrival to coincide with the start of the monsoon, hoping it will be the best time to find and follow a newborn calf. By drawing on local knowledge, Martyn begins to unravel the complex social world of Sri Lanka's elephants - he witnesses a fight over a calf, a battle between two bulls in musk and, at an elephant sanctuary, befriends an orphaned elephant who sadly lost a leg to a snare and is facing an uncertain future.
Giant insects once dominated the earth before the dinosaurs. Thanks to new technologies combining genetics, ethology, geology and even particle physics, paleontologists can now recreate the missing branches of the tree of life. Assumptions have been shattered and all the rules are changing.