Lewis is the first to complete long distance swims in every one of the world’s oceans – including the waters around the melting ice cap. He’s witnessed retreating glaciers, coral bleaching and changing patterns of migration, and now focuses on raising awareness of the fragile maritime environment. He’s also swum across a lake on Mount Everest to highlight the melting Himalayan glaciers. Aside from his environmental message, Lewis reveals his survival methods for extreme challenges.