Impel Down

Impel Down (インペル　ダウン), the Great Jail, 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. Some translations use the word Gaol which 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 for 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.

When a prisoner arrives in Impel Down they are put in boiling water to disinfect and sterilize them as well a "baptize" them. This is extremely painful, and only prisoners "of another league" (such as Ace, Jimbei and Crocodile) can stand it. Such prisoners don't even flinch, and enter "gracefully".

Aside from the Marine and their battleships, there are also guards throughout Impel Down. These are known as the Bullgory.

The prison is also monitored by a Surveillance Den Den Mushi. Tiny versions of them are found in specific locations throughout Impel Down, whatever they see is transferred to a larger version that sends video feeds to an machine it's connected too, allowing the guards to view video screens. Each of the smaller versions has an alarm beeper connected to the shells.

Impel Down Staff
Wardens
 * Magellan
 * Hannyabal

Guards
 * Domino
 * Bullgory
 * A minotaur

Current known prisoners

 * Sir Crocodile (Life sentence)
 * Daz Bones (Life sentence)
 * Mr. 2 Bon Kurei (Life sentence)
 * Mr. 3 (Life sentence)
 * Portgas D. Ace (Death penalty in 33 hours)
 * Jinbei (Temporarily sentence)
 * 500 pirates captured by Admiral Kizaru (Awaiting transfer)
 * Buggy the Clown (Vanished from cell, later teamed up with Luffy)

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 Kurei 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 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 capture at Impel Down. With Luffy currently breaking in Impel Down to rescue Ace, he has teamed up with Buggy to get there, and fight off any guards that come on their way.