The Volcanic Asteroid is a common name given to the asteroid within Dimension X where the Technodrome is located during season 4 (including the Vacation in Europe episodes) and early season 5 of the 1987–1996 animated series.
It has a breathable atmosphere, and consists of a lake in the central parts of one of the parts, and a mountain where the Technodrome is located when it's there. The mountain is volcanic, and errupts in the episode The Dimension X Story, burying the Technodrome deeper in the nearby lava.
The Blastorama Pleasuredome is also located there.[1]