Davina McCall: Life at the Extreme

Davina travels to the Azores in the mid-Atlantic to investigate how animals cope with with atmospheric pressure changes underwater, particularly the ones that have to take in air before they submerge. She swims with a school of dolphins and finds out about the inbuilt response that both animals and humans have when they go underwater, and meets a world champion freediver who teaches her the techniques needed to swim alongside sperm whales, before trying to overcome her nerves and dive down to the ocean floor on a single breath.

In episode three, Davina travels to the islands of Svalbard in the Arctic Circle. It's a harsh environment set across 15 million square kilometers of sea ice, where temperatures can drop to minus 40 degrees Celsius. Just 800 miles from the North Pole, her journey begins in Longyearbyen, one of the most Northerly towns in the world.

In the final episode of the series, Davina travels to the Costa Rican jungle, one of the wettest places on earth, a habitat in which animals thrive. Even with near 100 per cent humidity, and being less than a quarter of the size of the UK, it's home to a staggering 500,000 species of life.