In Tokyo, there are unapproachable "lost islands" with unspoiled environs and rich wildlife. Minami Iwo-to, part of the Ogasawara island chain, is about 1,300km from the Japanese capital. Normally, entry is banned to protect the environment. An exception was made in 2017 for the first comprehensive scientific survey in 10 years. The island compresses multiple climate zones into a small area, offering researchers a rare opportunity to view evolution in action. Braving an arduous climb and a swarm of seabirds, the team discovers one new species after another.
Going down into these narrow flooded passageways is not for the faint-hearted but, with only an estimated one percent of the caves explored, it is an opportunity for the team to write themselves into cave diving history, by pushing further in than anyone has before. This is a challenge that tests even the most accomplished cave divers. Steve must face the terrors of being lost in an underwater silt cloud in a cave. But there is a bigger issue at stake. All life in the Yucatan depends on the fresh water in this network of caves, but it's being contaminated by human development. With every metre the team maps, it adds to the knowledge of the system, which, in turns, helps protect it for future generations.
South America - the most species rich continent on Earth. From the volcanoes of the Andes to the world’s largest rainforest, the Amazon, animals here must specialise to carve out a niche. In Patagonia, a puma mother draws on a lifetime’s experience to catch prey three times her weight. In the cloud forest, rarely seen Andean bears clamber thirty metres into the canopy to find elusive fruit. Poison dart frogs use ingenious methods to keep their tadpoles safe, whilst anacondas stalk capuchin monkeys. At Igauzu, swifts make death-defying flights through one of the biggest waterfalls on Earth.
The Lake Erie water snake, once on the brink of extinction, now looks to be rebounding--thanks mainly to the invasive goby fish that's wreaking havoc on the Great Lakes ecosystem. Can scientists studying this environmental anomaly find a healthy ecological balance?
The Orange River travels almost two-thirds the length of South Africa to reach its most scenic checkpoint: The mighty Augrabies Falls. Widely regarded as one of the six great waterfalls on Earth, it is also an interminable source of hydration and food for the wildlife that live near its waters.