Valley of Bowser

The Valley of Bowser is the home of the Koopa King and his entire Clan, located within Dinosaur Land; a giant rock carving of Bowser's head that rises out of the sea serves as its entrance. The area is filled with dark caverns, lava, and frequent flashes of lightning; additionally, Bowser's castle is located here, Mario having once traveled many miles to reach it ("Super Mario World").

During the "Dimension" saga, the alliance makes its way here, but not before Doctor Eggman and his new alliance of the heroes' enemies ally themselves with Bowser and his forces. The Clash at the Valley of Bowser results in a massive brawl between both alliances, ending with the heroes' defeat. After the heroes are mysteriously transported away by an outside force, the Valley of Bowser later receives its own laboratory for technological development, courtesy of the Doctor, as he and his accomplices begin setting up their conquest of the planet and its alternate dimensions. This laboratory is later used by Kamek five years later, as he attempts to resurrect Gemerl the android. However, the result is catastrophic, in that Gemerl suddenly begins destroying everything and everyone around him, including Kamek; in the end, the Valley of Bowser is destroyed, signifying the end of the Koopas' reign in Dinosaur Land.