Waterland. The episode is set in the Bay of Bengal, 100 million years into the future. The episode focuses on three species: (1) Toraton, a descendant of the giant tortoise and the largest creature ever to walk the Earth. They can weigh up to 120 tonnes; (2) Swampus, a descendant of the octopus which has formed a symbiotic relationship with a plant to house its young. They are very intelligent; (3) Lurkfish, a descedant of the electric catfish that can fire up to 1000 volts to stun prey. They are ambush predators. The episode shows that at this point of the future, volcanoes are belching out copious amounts of greenhouse gases causing the planet to overheat. It shows how swampus breed and how toraton have evolved to cope with their new size.