The big blue is the world's greatest wilderness, far from shore and many kilometres deep. It's a vast marine desert where there is little to eat and nowhere to hide. Yet it's home to some of the biggest and most spectacular creatures on earth. This episode reveals what it takes to survive in this savage and forbidding world. We witness feats of incredible endurance, moments of high drama and extraordinary acts of heart-wrenching self-sacrifice. Every animal in the big blue must find their own unique way to survive. Sperm whales have the largest brains in the world. They live for 80 years, and we are only now beginning to learn the extraordinary complexity of their language of clicks - thought to coordinate the whole family in everything from childcare to hunting. With special pressure-proof cameras, we witness record-breaking feats of endurance as they hunt for squid a kilometre down into the abyss. Only recently have we begun to solve the mystery of where baby turtles disappear to in their early years. They leave the crowded waters of the coast and head to the open ocean, where they use floating debris like logs as life rafts. Here they remain until adulthood, adrift on the high seas in relative safety away from coastal predators. Over half of all animals in the open ocean drift in currents. Jellyfish cross entire oceans feeding on whatever happens to tangle with their tentacles. The jelly-like Portuguese man-of-war can harness sail power to fish with its deadly tentacles. Sometimes there is a brief explosion of food in this marine desert, but ocean hunters must be fast to make the best of this bonanza. We witness super pods of up to 5,000 spinner dolphins racing to herd vast shoals of lanternfish, briefly caught at the surface where it is thought they spawn. New aerial footage reveals, for the first time, the truth to a centuries-old sailors' legend of the 'boiling seas' - the spectacular feeding frenzy of 90kg tuna and dolphins smashing through the lantern fish shoals turning the sea white with foam.

Fly over Africa on the back of a vulture and see the most animal-packed continent with fresh eyes. Arrow-dive with cape gannets among sharks, dolphins and whales as they join the great sardine run. Soar with fish eagles as they discover an S-shaped living island comprised entirely of flamingos, and join them on a spectacular hunt. Fly with kelp gulls as they study the hunting behaviour of the greatest underwater predator of all: the great white shark. On the wings of eagles, fly through the mist-filled Victoria Falls and dive for fish in the mighty Zambezi. Circle with vultures high above the Serengeti as they watch the drama of the wildebeest migration below, and discover what happens when this canny scavenger suddenly becomes prey. Among toxic soda lakes, find out what it is like to be a flamingo, vulnerable to every predator on the continent, including baboons and hyenas. Join these flamingos as they take part in one of the most beautiful dances in the bird world. This is Africa as never seen before - from the wings of birds

Sir David Attenborough takes a breath-taking journey through the vast and diverse continent of Africa as it's never been seen before. From the richness of the Cape of Good Hope to blizzards in the high Atlas Mountains, from the brooding jungles of the Congo to the steaming swamps and misty savannahs, Africa explores the whole continent. An astonishing array of previously unknown places are revealed along with bizarre new creatures and extraordinary behaviours. Using the latest in filming technology including remote HD cameras, BBC One takes an animal's eye view of the action. The journey begins in the Kalahari, Africa's ancient southwest corner, where two extraordinary deserts sit side by side and even the most familiar of its creatures have developed ingenious survival techniques. Black rhinos reveal a lighter side to their character as they gather around a secret waterhole. Springbok celebrate the arrival of rains with a display of 'pronking'. Bull desert giraffes endure ferocious battles for territory in a dry river bed.

Could we get all our energy needs from sea water and the salt it contains? Are we to witness a time when salt will power our engines and factories, and light up our cities? Could this be the final curtain not only for shale gas and oil, but also the burning of fossil fuels and the beginning of a gentler form of energy that is definitely renewable? This documentary explores the latest research on sea water and the way scientists all over the world are working on 'Blue Energy'. This research could bring about a major change in our time.

Mars is filled with mysteries, Volcanoes 77 000 feet tall, Huge canyons, 3000 miles across and 6 miles deep, all kinds of interesting features. Awaiting you is some of the greatest scenery in our Solar System, on a world where water once ruled, then vanished into thin air. Where lost microbe empires may still survive underground. We've seen the postcards, and we do wish we were there.

Narrated by Ewan McGregor, Humpback Whales is an extraordinary journey into the mysterious world of one of nature's most awe-inspiring marine mammals. Set in the spectacular waters of Alaska, Hawaii and the remote islands of Tonga, this ocean adventure offers audiences an up-close look at how these whales communicate, sing, feed, play and take care of their young. Humpbacks were nearly driven to extinction 50 years ago, but today are making a slow but remarkable recovery. Join a team of researchers as they unlock the secrets of the humpback and find out why humpbacks are the most acrobatic of all whales, why they sing their haunting songs, and why these intelligent 55-foot, 50-ton animals migrate up to 10,000 miles round-trip every year.