David Attenborough travels to the end of the Earth, taking viewers on an extraordinary journey across the polar regions of our planet, North and South. The Arctic and Antarctic are the greatest and least-known wildernesses of all - magical ice worlds inhabited by the most bizarre and hardy creatures on Earth.

Our journey begins with David at the North Pole, as the sun returns after six months of darkness. We follow a pair of courting polar bears, which reveal a surprisingly tender side. Next stop is the giant Greenland ice cap, where waterfalls plunge into the heart of the ice and a colossal iceberg carves into the sea. Humpback whales join the largest gathering of seabirds on Earth to feast in rich Alaskan waters. Further south, the tree line marks the start of the taiga forest, containing one third of all trees on earth. Here, 25 of the world's largest wolves take on formidable bison prey.

At the other end of our planet, the Antarctic begins in the Southern Ocean, where surfing penguins struggle to escape a hungry sea lion and teams of orcas create giant waves to wash seals from ice floes - a filming first. Diving below the ice, we discover prehistoric giants, including terrifying sea spiders and woodlice the size of dinner plates. Above ground, crystal caverns ring the summit of Erebus, the most southerly volcano on earth. From here, we retrace the routes of early explorers across the formidable Antarctic ice cap - the largest expanse of ice on our planet. Finally, we rejoin David at the South Pole, exactly one hundred years after Amundsen, and then Scott, were the first humans to stand there.

It is high summer in the polar regions, and the sun never sets. Vast hordes of summer visitors cram a lifetime of drama into one long, magical day. They must feed, fight and rear their young in this brief window of plenty.

Summer is a tough time for the polar bear family, as their ice world melts away and the cubs take their first swimming lesson. Some bears save energy by dozing on icy sunbeds, while others go egg-collecting in an arctic tern colony, braving bombardment by sharp beaks.

There are even bigger battles on the tundra - a herd of musk oxen gallop to the rescue as a calf is caught in a life and death struggle with a pair of arctic wolves. But summer also brings surprises, as a huge colony of 400,000 king penguins cope with an unlikely problem - heat. The adults go surfing, while the woolly-coated chicks take a cooling mud bath.

Nearby, a bull fur seal is prepared to fight to the death with a rival. Fur flies as the little pups struggle desperately to keep out of the way of the duelling giants.

Further south, a minke whale is hunted amongst the ice floes by a family of killer whales. The dramatic chase lasts over two hours and has never been filmed before. The killers harry the minke whale, taking it in turns to wear it down. Eventually it succumbs to the relentless battering. Finally, comical adelie penguins waddle back to their 500,000-strong colony like clockwork toys. The fluffy chicks need constant feeding and protection as piratical skuas patrol the skies. When an unguarded chick is snatched, a dramatic dogfight ensues.