The Swamp of Boggy Ben is a marshy area located on Third Earth. It is a hideous and uninviting place made up mostly of greenish swampland. The swamp is the home of the gigantic creature known as Boggy Ben. A number of other strange creatures also reside there including Flesh-Eating Spiders, Ghastly Trees, Swamp Lizards and Talking Frogs among others. There are also massive skulls floating in the swamp, most likely belonging to victims of Boggy Ben. In the middle of the swamp is Boggy Ben's Lair, where the creature resides.
In "The Legend of Boggy Ben", the ThunderCats journeyed to the swamp in search of the Elixir of Jar-Opening Super Strength, a potion that Cheetara had made up. They eventually ended up battling and defeating Boggy Ben.