Winter

Alaska is one of the most iconic wildernesses on the planet - America's last frontier.

This three-part series follows a year in Alaska, revealing the stories of pioneering Alaskans, both animal and human, as they battle the elements and reap the benefits of nature's seasonal gold rush.

Alaska is huge - by far the biggest US state - and still one of the wildest places on earth. It has deep forests and vast mountain ranges, and a third of it sits above the Arctic Circle. The whole state goes through some of the most extreme seasonal changes: temperatures can reach into the 90s F (30s C) in the summer and can plummet to -80F (-60C) in the winter.

Yet plenty survives here - Alaska is home to some of the hardiest animals on the planet. Each one has its own quirky way of getting through the challenges of the seasons. Above all, this is a land of great characters.

Black bear cubs are faced with a daunting climb down from their tree den and a mother sea otter nurses her baby through the chilly days of early spring. Stealthy 50-tonne sperm whales steal fish from the end of fishermen's lines in an extraordinary marine 'heist', grizzly bears grow big on a sudden wealth of salmon, and a huge male moose finds unlikely ways to impress a female. Thousands of bald eagles gather for a winter feast, and arctic foxes risk everything to find food in the alien world of an oil boomtown. People, too, must go with the flow of the extreme seasons, facing winter storms at sea to catch snow crabs, rushing across ice rivers with teams of huskies and taking advantage of Alaska's endless summer daylight to grow world-class giant vegetables.

Surviving the bone-chilling cold, deadly blizzards and darkness of an Alaskan winter takes courage, cunning and remarkable endurance. In the raw beauty of windswept mountain peaks, icy tundra and snowbound forests, this is the story of the tough and resourceful characters that face up to the ultimate challenges of this untameable land.