The Blue Planet

The oceans are an integral part of the Earth's life cycle, influencing weather systems and supporting a huge range of life. The series opener explores the sheer scale, power and complexity of the oceans that govern the planet.

Explore a world of mountain ranges, perpetual night, pressure extremes and the weirdest life forms on the planet. Embark on a voyage into the unknown, where fish with cavernous mouths and cruel teeth lurk below the surface.

Where the sea bed drops a staggering eight kilometers and the nearest island is 500 kilometers away, there is nothing but the burning sun above and the blackened abyss below. Find out what life forms exist in this blue expanse.

Life on the edge of a frozen sea is tough, but in the spring life begins again. Plankton blooms and feeds hordes of migrating fish. Birds, whales, seals and polar bears gorge themselves before the ice pushes them from the land.

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

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 protection.

The boundary between land and sea is an exciting place with animals constantly coming and going, from millions of seabirds forced to come onto land to breed to killer whales crashing in on the surf to snatch young sea lions.