Known as the Underwater Great Prison, Impel Down serves as one of the World Government's primary controlled strongholds, alongside the Marine Headquarters and Enies Lobby. With each Level It is the World Government's maximum-security prison for the most dangerous criminals and pirates. It is located underwater in the middle of the Calm Belt and part of the Tarai Current. Impel Down is the main setting of the Impel Down Arc, with the prison's staff