At the Extreme Environments Lab in the north of England, elite sailors are quite literally thrown in the deep end, undergoing harrowing survival training in a pool as close to the Southern Ocean as you'll find under one roof.

"I think for quite a lot of them it's all a bit of a game to start with — they're all jumping in the pool and having a bit of a laugh," Alistair Hackett, who runs the three-day advanced sea survival course at South Tyneside College in Newcastle, told CNN. "Then we turn the waves on. Then we turn the rain on and it's pretty severe — you can't really breathe properly with it hitting your face. Then we turn the wind on and all of a sudden it's not quite like going to your local swimming pool anymore."

Shirley Robertson, a two-time Olympic gold medal winning sailor turned broadcaster, recently underwent the grueling testing for an in-depth report for CNN.