The Banoi Maximum Security Prison is the final location featured in Dead Island comprising the entirety of Act IV. The prison is located on a small island off the shores of Banoi Island, and is surrounded by a minefield. It was designed as a maximum security facility for international terrorists.
At the end of Act II, the Hero is able to make contact with the "Voice" from the top of the resort hotel. He informs the Hero he is a Colonel in the Banoi Island Defense Force currently holed up in the prison. In order to reach him, the Hero must travel to Mingende and talk to the smuggler, Mowen, to act as a guide through the mine-infested waters.
After reaching Mowen and finding Yerema in the process, the Hero has the option to finish Act III and proceed to the prison. Prior to traveling to the prison, it is recommended the player makes sure to accomplish everything needed in the Resort, Moresby, and the Jungle. Once the Hero heads to the prison, it is impossible to go back to the other parts of the island until completing the game.
The prison is made up of numerous cell blocks spanning the first few floors, with several offices on the upper stories which are used by the senior guards. Most of the inmates are holed up in the canteen, which is just a short distance from the building's kitchen. An armory is also located on one of the floors, which will need to be broken into during one of the missions for Titus Kabui.
- Since it is an island prison it is a bit similar to Alcatraz Prison in San Francisco.
- In the cafeteria next to a prisoner named Harland, there is a prisoner that is simply labelled as "Human".
- The outside of the prison cannot be seen in detail during the events of Dead Island, except for basic texture/structures meant only to be visible from afar.
- When playing Ryder White's Campaign, the player is able to go outside and see a portion of the prison, opposite the side facing the resort.
- The player is able to visit more areas within the prison in Ryder White's Campaign, including extra floors of the hospital, the hospital basement, laundry room, and death row (complete with a working electric chair).
- In the last death row cell on the left, coming from the electric chair, the player will find a closed toilet. Opening the toilet will reveal bloody water, with a hand reaching out. Below the bowl of the toilet are the words, "Don't Open Dead Inside." This is a direct reference to the comic book series, The Walking Dead, which takes place after a zombie infection. When the protagonist wakes up in the hospital, he sees a set of doors with the same message.
- The monitors in the hotel's control room show the same images as the prison control room's monitors.
- Glitches frequently occur with the dead bodies within the Prison. It happens more often in the Prison than in other locations. The bodies either spazz out or are reduced to a tiny size. Techland has yet to address this issue. Example video of said glitch provided.
- On the wall just outside the canteen, one of Howard Craigson's posters can be found.
- Occasionally, infected will spawn in the hallway on the opposite side of the medical office wall, react to the player, and try to run through the wall.