Andy Torbet takes on a mission to match the deep-dwelling giant Japanese spider crab. Capable of living at depths as low as 600m, these crabs have amazing protective shells which withstand the pressure of the ocean water pushing down on them. His journey begins in Italy where he visits the world's deepest swimming pool, Y-40, to learn what happens to the body when submerged under many metres of water. Andy also heads to Catalina Island off the California coast for a trip in a submarine, coming face to face with some colourful fish in the process. Finally, he heads to Vancouver in Canada to try out a unique, wearable hard-suit diving system. But will his efforts enable him to complete some tricky, crab-inspired tasks?