Impel Down

Impel Down, the Great Gaol, is the World Government's maximum-security prison for the most dangerous criminals and pirates. Its name derives from The English verb 'impel', meaning to force. Gaol is an early Modern English spelling for jail.

It is located underwater in the middle of a Calm Belt. To get there with the greatest of ease, one must use a water current accessible by going through the Gates of Justice located at either the Marine Headquarters or Enies Lobby. By using this water current located between these three locations, the amount of time for traveling between these locations is also cut by a considerable amount.

Current known prisoners
Crocodile and Mr. 1 were imprisoned in a Marine base, but were transferred to Impel Down after most of the captured Baroque Works members escaped (Crocodile and Mr. 1 chose to stay behind). Bon Clay and Mr. 3 were captured by Hina, and presumably transferred to Impel Down for reasons similar to Crocodile and Mr. 1's transfers.
 * Sir Crocodile
 * Das Bones
 * Mr. 2 Bon Kurei
 * Mr. 3
 * Portgas D. Ace
 * Jimbei
 * 500 pirates captured by Admiral Kizaru

Defeating Portgas D. Ace led to Blackbeard becoming a Shichibukai, and Ace being sent to Impel Down. Ace is currently sentenced to public execution.

During the Sabaody Archipelago incident, Kizaru captured 500 pirates, and all of them are currently being transferred into Impel Down.

Jimbei has caused a wild outburst during his summons in the Marine HQ, and is sent to Impel Down until he is calmed, but he shows no sign in folding.