Blue Shark

Steve tracks down the ultimate aquatic athlete. Taking mega-migrations around the Atlantic and Pacific oceans, the blue sharks are ocean Olympians. Steve catches up with a couple of these bolts of blue off the Californian coast, before heading to the Shark Lab to reveal how these canny creatures rely on their liver to provide buoyancy, and hitch a ride on ocean currents, allowing these athletes to make mega-migrations across the great oceans.