Enter the fascinating world of the coral reefs and experience breath taking flora and fauna up close. The multitude of marine species, commencing with glassy sweepers, blow and porcupine fish, goliath groupers, giant morays, sea turtles up to the largest shark on earth, the whale shark, as well as the play of colours and the biodiversity of the corals, stony star corals, soft corals, bubble-tip anemones and gorgonian corals. Let yourself fall into a rapture of the deep. All in glorious 3D

Fly across iridescent tropical reefs, brush through a cloud of a million jellyfish, visit an alien world where the closer you look, the more you see, where the tiniest creatures support the greatest predators... We think of reefs as exotic, distant places with little or no connection to our everyday world. Yet every reef is a living city beneath the sea with a parallel existence to ours, distant yet undeniably connected. Reefs are hotspots of biodiversity as vital to life on earth as the rain-forests. They have been shaping our shorelines, literally forming islands and mountains, for millions of years. The fossil record shows that given time they have recovered from all of earth's major extinction events. Even reefs pulverised by atomic blasts at Bikini Atoll have regenerated. Yet within our lifetime reefs have come to face their greatest threat...

There is no greater test for life than winter, as temperatures plummet to 70 below and winds reach 200kph. Darkness and ice extend across the polar regions and only a few remarkable survivors gamble on remaining. We join a female polar bear trekking into the Arctic mountains to give birth as the first blizzards arrive. Out on the frozen ocean, the entire world's population of spectacled eider ducks brave the winter in a giant ice hole kept open by ferocious currents. Arctic forests transform into a wonderland of frost and snow - the scene of a desperate and bloody battle between wolf and bison, but also where a remarkable alliance between raven and wolverine is made. Beneath the snow lies a magical world of winter survivors. Here tiny voles dodge the clutches of the great grey owl, but cannot escape the ultimate under-show predator - the least weasel. Midwinter and a male polar bear wanders alone across the dark, empty icescape. Below the snow, polar bear cubs begin life in an icy den while fantastical auroras light the night skies above. In Antarctica, we join male emperor penguins in their darkest hour, battling to protect precious eggs from fierce polar storms. Weddell seals escape to a hidden world of jewel-coloured corals and alien-looking creatures but frozen devastation follows as sinister ice stalactites reach down with deadly effect.

Marine invertebrates are some of the most bizarre and beautiful animals on the planet, and thrive in the toughest parts of the oceans. Divers swim into a shoal of predatory Humboldt squid as they emerge from the ocean depths to hunt in packs. When cuttlefish gather to mate, their bodies flash in stroboscopic colours. Time-lapse photography reveals thousands of starfish gathering under the Arctic ice to devour a seal carcass. A giant octopus commits suicide for her young. A camera follows her into a cave which she walls up, then she protects her eggs until she starves. The greatest living structures on earth, coral reefs, are created by tiny animals in some of the world's most inhospitable waters.

The tropical Indian Ocean is home to the Spice Islands. Characterised by beautiful sandy beaches, fringing coral reefs and coastal mangrove forests, this is a vibrant nursery area for marine life, such as whale sharks, crabs, seahorses and a great variety of fish. The coastal areas are where humans have the most direct impact on the ocean's resources.

The extraordinary wildlife, culture and history of this immense, fascinating ocean and its myriad islands are revealed in stunning detail. With its coral reefs, turquoise lagoons and dramatic oceanic atolls, the South Pacific is the archetypal paradise. It is still relatively healthy and teeming with fish, but it is a fragile paradise. International fishing fleets are taking a serious toll on the sharks, albatross and tuna, and there are other insidious threats to these bountiful seas. We look at what is being done to preserve the ocean and its wildlife.