The teams grab their cameras and diving gear and hit the turquoise waters of the Maldives, where rare silvertips lurk and ferocious tiger sharks circle.
Along Australia's Great Barrier Reef, the teams get the rare chance to dive at night. Between bamboo sharks and wobbegongs, the race is gill and gill.
Brutal currents and jellyfish stings make Japan the most challenging dive yet — but the prospect of seeing a sharknado keeps the group's spirits afloat.
Low visibility and an imminent elimination create choppy competition in South Africa. Still, the teams are determined: Will they find a great white?