Impel Down

Impel Down (Inperu Daun), 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 only way 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. Also, the only way to safely get to the prison is to use one of the seastone lined Marine battleships as the entire place is surrounded by Sea Kings.

Layout
Impel Down is a large submerged tower like structure that whose foundation is at the very bottom of the sea bed. Due to it being built within the Calm Belt, the entire structure is constantly surrounded by gigantic Sea King swimming alongside underneath the waves. Along with these beasts, the prison is guarded by a force of Marine battleships and crew greater than any Buster Call.

Within the dark confines of the prison are various cells and torture chambers that used for the prisoners. The torture chambers are used for all sorts of brutal unspeakable acts. Among these include continuous whipping, brutal beating to death, boiling cauldrons for burning and drowning, and spiked pits used to impaling.

According to Nami, Impel Down is where the world's most dangerous criminals are sentenced to, and with all its torturous ways, no mercy is ever given to the prisoners. As seen, some prisoners are tortured to the point where they beg for death, while others are driven to the point of enjoying watching others suffer. Apparently, if the prisoners have a little fight, then they would be placed in death row and locked up in a cell where they would be brutally beaten to death by an unknown force. Also, according to Alvida, the prison is impossible to infiltrate or escape.

Aside from the Marine and their battleships, there are also guards placed within the gaol. Also, there seems to be a bipedal bull-like creature to guard and sentence troublemakers to death row.

Current known prisoners

 * Sir Crocodile
 * Mr. 1
 * Mr. 2 Bon Kurei
 * Mr. 3
 * Portgas D. Ace
 * Jinbei
 * 500 pirates captured by Admiral Kizaru
 * Buggy the Clown

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.

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.

Jinbei 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.

Buggy the Clown was transferred here presumably after being captured after leaving the island he mistook for Treasure Island. Buggy managed to escape his cage in Impel Down, but it is unknown whether his acquaintance with Ace has any effect on his recent escape at Impel Down.