Andy Torbet travels to Alaska in his quest to swim like a seal in freezing lake water, under a sheet of ice. His journey begins off the Northumberland coast, diving with grey seals to learn how insulating, fatty blubber gives them unrivalled resistance to the cold. Next, Andy meets Olympic medallist Keri-anne Payne and discovers how cold-water shock affects his body. Then Andy tests out blubber-like insulating technology while being dunked in the Extreme Environments Lab pool at Portsmouth University. Will this chilly challenge see him sink or swim?