Ocean Giants

Antarctica - a land of survivors enduring the most hostile conditions on earth. 98 per cent of the mainland is covered by ice on which virtually nothing can live. Even the sea freezes over, but the Weddell seal manages to survive here by keeping its breathing holes open by using its teeth to grind away the ice.

The new tools and technology that are pushing the limits in the world's most unruly bodies of water, including an ocean miner used to extract salts that are used to manufacture plastics, multi-mission fireboats, and the world's biggest tidal turbine. The biggest, most advanced fireboats in the world carry superhero behemoths, using cutting-edge engineering and technology to keep a critical American port safe from deadly fires.

Broadcast 3 March 2008, the final programme covers the most ancient of the reptiles: the crocodiles and turtles. In the Galápagos Islands, among the giant tortoises, Attenborough explains how the creatures came to develop their shells as a defence against predators. This is demonstrated by the eastern box turtle, whose shell includes a hinged ‘drawbridge’. The aquatic pig-nosed turtle is unusual in that its eggs need to be submerged before hatching, whereas those of other species would drown; Attenborough illustrates this by dropping an egg into a jar of water: it immediately hatches. In the open ocean, male sea turtles attempt to separate a rival from its mate by attacking and overwhelming the pair, stopping them from taking in air. In northern Australia, Attenborough observes a large gathering of crocodiles at a flooded coastal road: they time their arrival to ambush migrating mullet. The complex communication and body language of the American alligator is investigated and in Argentina, the calls of young caimans help their mother locate and lead them to a nursery pool. The mother’s maternal instinct extends to releasing unhatched babies by gently crushing their eggs in its jaws. In Venezuela, a female spectacled caiman in charge of an entire crèche leads the infants from a drying river bed on a trek to permanent water. Under the Skin explores filming on the Galápagos Islands and Attenborough’s meeting with Lonesome George.

South African extreme angler Andy Coetzee has traveled the oceans to reel in the world's largest, most elusive fish. And as we're about to find out, he's willing to do anything, even risk his own life, to catch them. Watch him brave one of the most treacherous rivers on the planet, enter uncharted regions of the Indian Ocean, and dive into the predator-laden waters of Western Africa on his quest to find the Nile perch, the dogtooth tuna, and the giant barracuda–three leviathans that won't be caught without a fight.

The Auckland Islands are an isolated archipelago of islands far south of New Zealand. They might seem bleak, but they are a surprising sanctuary for wildlife. In summer, hordes of giant sea lions descend upon a desolate beach, and testosterone-driven males begin bloody battles for mating rights. When the pregnant females return to give birth on the beach, chaos ensues. The pups are always in danger of being squashed by overly eager males. Some of the rarest penguins on the planet, the yellow-eyed penguins, are also breeding here and must constantly evade the huge brawling male sea lions.