The Deep Prison, also referred to as The Tomb, was an enormous prison facility established by the Infinite Empire on the world of Belsavis. The Galactic Republic subsequently integrated it into the larger Belsavis prison system.
Fifty years prior to the Great Galactic War, the Galactic Republic came upon it and the Strategic Information Service transformed it into a Republic correctional facility. It served as a detention center for Mandalorians, Sith Lords, and Sithspawn throughout the Great War. Throughout that conflict, the Sith Empire dispatched combat units to the planet, aiming to liberate their incarcerated comrades.
Executor Krannus once planned to cause the Rakatan power core, situated in the subterranean levels, to go into meltdown. This action would have triggered a hyperspace disturbance capable of obliterating the entire planetary system.