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. The 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.

Because of it's brutal nature and being renowned for being inescapable, almost no person pirate or other wise wishes to ever go there, however there are people who choose to enter it willingly such as Luffy and Crocodile.

General 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.

The prison is carefully monitored all around 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 a 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.

Levels
When a prisoner arrives in Impel Down they are put in boiling water to disinfect and sterilize them. This is ritually referred to as "baptizing" them. While most have screamed in pain due to the extreme heat, only a few prisoners have been known to take the sterilization without flinching even one bit. These prisoners include Ace, Jinbei, and Crocodile. After being sterilized, they are then placed in one of the five known levels of Impel Down based on their crimes and strength. The more heinous or powerful a prisoner is, the lower the level they will be placed.

Along with various cells to keep inmates, each level possesses a unique form of torture. Because of these unspeakable acts being performed, each level is given the title of hell.

Level 1: Crimson Hell
The first level of Impel Down in which prisoners are kept in. While the level relatively is used for less wanted criminals, it contains a large forest of red trees. The leaves of the trees, known as Kenju (剣樹), are as sharp as blades while the grass on the floor, the Haribarisou (針グ草), is as spiky as needles. Here prisoners are forced to run through the forest while being chased by poisonous spiders and guards to experience all the pain from being cut from all directions. As consequence of prisoners being forced through this forest, it is soaked in blood. Deep within the forest is a hole that leads to level 2. For those who do not wish to live through the pain of being cut any longer, they were given the option of jumping down the hole to level 2, which rests an even more terrifying hell that nobody is willing to use.

Level 2: Wild Beast Hell
The second level of Impel Down in which prisoners are kept in. It contains wild beasts of sorts. One of these wild beasts is the "basilisk." In the world of One Piece it is a snake born from a chicken. It is said to be extremely strong and gives Luffy and Buggy a good chase, but is then almost immediately downed with one blow of Gear Third from Luffy. The prisoners consider the "boss" of level 2 however to not be the basilisk, and they are still very frightened of leaving their cells after the basilisk is defeated.

Level 3
The third level of Impel Down in which prisoners are kept in. Not much is currently known about this level. We do know however that Mr. 3 has agreed to lead Buggy and Luffy to this level.

Level 4: Scorching Hell
The fourth level of Impel Down in which prisoners are kept in. Prisoners from other levels are regularly tortured here. For example, Buggy said he went through "Inferno torture" on this level. Magellan the warden of Impel Down stays here.

Level 5
The fifth level of Impel Down in which prisoners are kept in. This is level is where criminals whose bounties are more than 100,000,000 are kept. Ace and Jinbei are said to being kept here.

Level 6 (Rumor)
A mysterious level rumored by the prisoners to exist deeper than Level 5. It is said to keep criminals who are so powerful and dangerous that they have been erased by history by being kept here.

Impel Down Staff
Wardens
 * Magellan
 * Hannyabal

Guards
 * Domino
 * Blue Gorillas
 * a minotaur
 * a basilisk
 * presumedly other various mythical creatures

Current known prisoners

 * Sir Crocodile (Life sentence)
 * Mr. 1 Daz Bones (Life sentence)
 * Mr. 2 Bon Kurei (Life sentence)
 * Mr. 3 (Life sentence) (Level 2) (Released from cell by Buggy. Now teaming up with Luffy and Buggy)
 * Portgas D. Ace (Death penalty in less than 33 hours) (Level 5)
 * Jinbei (Temporarily sentenced) (Level 5)
 * 500 pirates captured by Admiral Kizaru (Awaiting transfer)
 * Buggy the Clown (Vanished from cell, later teamed up with Luffy and Mr. 3) (Currently at large on Level 2)

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.