Devil's Gulag, more properly known as the Devil's Island Gulag, was once the primary prison used by the Kingdom of Acorn to hold its most dangerous captives. A fortress situated atop a tall spire in the middle of a ring of active volcanoes, the gulag is surrounded by boiling ocean waters at a temperature of 220 degrees Farenheit, hence it's name. These features, combined with the security of the fortress itself, made escape seem an impossibility. However, due to the intervention of Dr. Eggman and his orbiting satellites, all of Devil's Gulag's inmates escaped during Sonic the Hedgehog's search for Ixis Naugus. A number of them would later be returned there, only to escape again; following the reclamation of Mobotropolis and its return to being Robotropolis due to Eggman's machinations, prisoners were kept in an unsophisticated prison in Knothole. Following the destruction of that city, a new high security penitentiary was designed and created by NICOLE, thus rendering Devil's Gulag redundant and effectively abandoned.