Blue Planet

The oceans dominate our planet while still remaining largely unexplored and mysterious. Their influence dominates the world's weather systems. They support an enormous range of life, from the largest whales to the smallest plankton, from hordes of sea birds to lonely, deep-sea fish. All this is governed by a complex system of biological and physical forces. This first episode demonstrates the sheer scale, power and complexity of the 'Blue Planet.'

A place of mountain ranges, perpetual night, pressure extremes, and cold... and the strangest life forms on our planet. A true voyage into the unknown with constant surprises in store. Fish with grotesquely cavernous mouths and cruel teeth lurk one mile below the surface. Any light is living light, and a glow in the dark may be meant to attract the opposite sex, unless it is the deep-sea angler fish who already has her mate conveniently fused to the end of her nose.

A void. Endless blue stretches in every direction. The sea bed is a staggering eight miles deeper down and the nearest island is 500 miles away. There is nothing save the burning sun above and the blackened abyss below. How, then, does life exist?

Life on the edge of a frozen sea is tough. Pack-ice at both poles is constantly on the move, and in winter freezes solid with air temperatures 70°C below freezing. Only in spring, with the retreating ice and light reaching the water, does life begin again.

Shafts of sunlight radiate through a green sea. This blazing light is the vital source of energy used by the countless billions of plankton which grow every spring and summer in the world's temperate sea, the richest of all habitats.

Bathed in warm, clear tropical water and brilliant sunlight, coral reefs are the rainforests of the sea. Surrounded by ocean deserts they are rich oases of life. Spectacular numbers make it necessary to stand out and survive. This competition is highly visible as brightly coloured fish compete for food, territory and mates. But the corals themselves are also dynamic. Incredible time-lapse photography shows the dramatic formation of a coral reef.

Tides govern marine life. Tidal marshes are one of the most productive parts of the world. Numerous plants support numerous animals, yet life is not easy: predators are attracted to these enormous quantities of food, forcing animals to seek constant protection from attack. Relief comes with the crashing waves, as the tides flow once more. Between the tides, when the sands become depleted of food and air, the worms, clams and shrimps just endure the expected pause.

The boundary between land and sea is an exciting place, with animals constantly coming and going. From the open oceans, millions of seabirds are forced to come onto land to breed. Sea eagles steal kittiwake chicks from their nesting ledges. Turtles lay their eggs in the sand and marine mammals haul themselves out to fight on the beaches. Sea-lions emerge from the kelp to give birth, while killer whales come crashing in on the surf to snatch the sea lions' young.