Waterland The episode is set in Kolkata, India, 100 million years in the future. The episode focuses on three species: (1) Toraton, a descendant of the giant tortoise and, at 120 tons, the largest creature ever to walk the Earth; (2) Swampus, a descendant of the octopus which has formed a symbiotic relationship with a plant to house its young; (3) Lurkfish, a descendant of the electric catfish that is an ambush predator and can fire up to 1000 volts to stun prey. The episode shows that at this point in the future, the large amount of greenhouse gases generated by volcanoes have caused the planet to overheat. It is also explored how Swampuses breed and how Toratons have evolved to cope with their massive size.