| ||For the quest, see Vault 81 (quest).|
Vault 81 is unlike almost any other known vault in the Commonwealth, in that it still contains sane and active dwellers. The old overseer's terminal (which is stored in the generator room) makes a heavy implication that this success is not due to them having a more benign experiment to conduct (like with Vault 101), but rather because the original overseer actively sabotaged Vault-Tec's original mandate by refusing to carry out the initial experiments.
Vault-Tec created Vault 81 with the purpose of developing a single, universal cure for every sickness that humanity could possibly suffer from, using the residents as human test subjects. The vault was divided into two separate areas; the main vault, where up to 96 residents would make their home for the foreseeable future and the secret vault, where Vault-Tec scientists would conduct their research and observe the residents as they were unknowingly exposed to different diseases and cures. The diseases were released via propellant nozzles hidden within the resident's rooms. In the case of an evacuation of the vault, all main vault residents were to be incinerated with the same propulsion nozzles.
The first vault overseer, Dr. Olivette was skeptical of Vault-Tec's goal and possible use of human experimentation. She planned to blow the whistle if it was found to be unethical. However, when she received her full briefing she found out the true nature of the experiment she also discovered that Vault-Tec had major backers in the federal government, rendering blowing the whistle as moot. Dr. Olivette was determined to not let the residents of the vault be used as guinea pigs and tried to think of a plan. On the morning of the Great War, Dr. Olivette received the "call" to start the notification of staff and residents, but sabotaged the call list so the science staff wouldn't be notified and report in. Her plan mostly worked; however, three of the science staff turned up. Kenneth Collins and Jim Flint came over with the general population and the third one Burrow, was visiting to ask when the next drill would be. As the three scientists worked to create their cure, Olivette watched over all of their data and personally had to approve the scientists moving onto Phases II and III, animal testing and human testing on unknowing participants respectively.
Before human testings could begin, Olivette disabled the delivery systems, cutting off the scientists from infecting the vault dwellers. Additionally, she also sealed all access points to the secret vault, leaving the three scientists to die. To prevent any commotion within the general population, Olivette kept the vault's true purpose and the existence of the secret vault, a closely guarded secret.
Isolated from the other side of the vault the scientists continued to use animal testing with their last remaining population of mole rats. To help with the research, Dr. Collins modified a Miss Nanny lab assistant to take on greater responsibilities due to the staff shortage, creating Curie. When the scientists eventually died of old age, Curie remained and worked on the cure alone, spending decades conducting trial after trial. She achieved the vault's objective in 2204, perfecting the universal cure. Although Curie had reached a level of self-awareness over the years she was unable to overcome her original programming, which required authorization from a Vault-Tec employee in order for her to leave the vault and begin a new line of research. She patiently idled in the secret vault for decades, awaiting a response from vault security.
Meanwhile, the residents in the main vault went on with their lives completely unaware that anything was amiss, or that they had been intended as test subjects. In 2277 Overseer Baht opened the vault for the first time, allowing communication and trade with the outside world. Although this provided a badly needed source of food and other vital supplies, especially parts and tools to repair the vault's deteriorating systems many residents maintained an isolationist or even xenophobic mindset, distrusting any outsider who was allowed to enter.
In 2287 Bobby De Luca, one of Vault 81's dwellers had discovered one of the entrances into the secret vault and used it to store his drugs. Austin Engill witnessed Bobby opening the door and went in to investigate. He was bitten by one of the lab mole rats, which had escaped containment and started a colony in the secret vault decades before. This nest was still infected with the various diseases used in the experiment, resulting in Austin acquiring an unknown lethal disease. When Bobby revealed the existence of the secret vault, the Sole Survivor agreed to search it for a potential cure. Inside, the Sole Survivor discovered Curie who handed over the last unexpired dose of her universal cure. The Sole Survivor could either use it on themself, leaving Austin to perish and earning the animosity of the vault dwellers, or turn it over to save Austin and be granted a room in the vault by Overseer McNamara and appreciation throughout the vault.
Vault 81 is divided into two main areas: the regular vault, where the residents live, and the secret observation area, where the scientific team used to observe the vault dwellers and conduct research. By 2287, the secret area is overrun by a special breed of mole rats while the regular vault is still functional and inhabited by vault dwellers.
There are two entrances from the main vault to the secret vault: an elevator located in the lobby, and a secret door in the reactor room. Although the elevator cannot be used until the end of the quest Hole in the Wall and the secret door is not unlocked before the beginning of the same quest.
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Secret Vault 81
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- Grognak the Barbarian issue #5 - In the classroom, as a reward for the side quest Short Stories.
- Taboo Tattoos issue #16 - In Horatio's barbershop.
- Overseer's Guardian - Sold by Alexis Combes. She also has Destroyer's right leg and overseer's armor.
- Overseer's room key - On Jacob Forsythe and Gwen McNamara, opens sliding door in the overseer's room.
- Vault 81 security key - On Scott Edwards and the vault security personnel. Gives access to various doors in Vault 81.
- Technician's note - Next to the old overseer's terminal in a small room underneath the stairs in the basement where Tina De Luca and Old Rusty work.
- Syringer rifle - Reward from the quest Hole in the Wall.
- Teddy bear - A unique clean variant can be found in a box before one of the beds in the northeast bedroom.
- 6 undamaged American flags can be found throughout the vault.
- A complete Giddyup Buttercup can be found in the room diagonally across from Bobby De Luca's room, to the right of the restroom.
Secret Vault 81
- Mini nuke - In the broodmother's room, inside a tipped over locker.
- Vault 81 tech password - In the research comm room. The password gives access to nearby secure access terminal.
- Stealth Boy - In same room as above.
- Medicine bobblehead - In Curie's laboratory.
- Vault 81
- Hole in the Wall
- Here Kitty, Kitty
- Short Stories
- Maintenance Man
- Fertilizer Woman
- If the vault is accessed by passing the Charisma check, one will still need to speak to McNamara before access to the elevator is gained.
- Although Dr. Penske has a lab in which the vault appears to grow its crops, there does not appear to be a water purifier. How the vault gets their water is never clarified.
- If one is bitten by the mole rats in Vault 81, their maximum HP will be reduced by 10 points until the vaccine from the quest Hole in the Wall is used. This will however affect the outcome of said quest negatively.
- If one manages to escape without being bitten, the cure can safely be given to Austin and the quest is completed without suffering from the health penalty.
- The virus will also be contracted if a companion is bitten.
- If one is still wearing the Vault 111 suit, the Vault 81 inhabitants will comment on their vault suit. Although sometimes they will comment on the player character being from a vault without them wearing the vault suit, or having interacted with them before.
- If one brings Codsworth, the Vault 81 inhabitants will compare it to their vault's Old Rusty.
- If one brings Dogmeat, Preston Garvey, MacCready, Cait, Paladin Danse, Hancock, Strong, Piper or Nick Valentine, the vault security will ask Overseer McNamara for permission to allow entrance.
- There is an audio file for if you have a second companion along with Dogmeat when first entering. This is only accessible either in the game files or through using mods such as "Everybody's Best Friend" that allow you to have an extra companion.
- If one brings Deacon, he will change his disguise into a Vault 81 jumpsuit.
- If one brings Paladin Danse, vault security will sarcastically question his seriousness.
- If one brings X6-88, some dwellers may recognize him as an Institute courser.
- If one brings Curie (after enabling her as a companion), she will request to leave the vault, even though she will still follow the player character.
- If one is wearing a suit of power armor, there will be numerous comments of both fear and admiration from the residents.
- If one is wearing a Silver Shroud costume, there will be comments about it being Halloween already.
- Following the successful completion of Hole in the Wall, the player character will be given a room by Gwen McNamara.
- In a strange twist of fortunate irony, the original overseer's change of heart led to the vault serving in its advertised role: "A shelter for its residents in the event of a nuclear attack."
- In the reactor area, five wooden blocks can be found on top of two machines, spelling out "BS" and "LOL."
- Fusion cores handed in can be anything from 1/100 to 100/100.
- When first entering the vault, the Sole Survivor will be asked to go see Dr. Forsythe. He will then ask for a donation of blood for his research, to study the change in the human DNA.
- In a random encounter, the location of Vault 81 can be marked on the map by speaking to Rylee, a Vault 81 resident who left to explore the Commonwealth.
- In another random encounter, the player character can come across a band of raiders holding a Vault 81 resident hostage. Upon killing the raiders, should the vault dweller survive, he will thank the player character and return to his vault.
- It's also possible to get Vault 81 marked on the map by picking up Dr. Forsythe's note, if found in the Commonwealth.
- All the clocks in the vault are stuck at 9:47, meaning the residents have made no effort to repair them, even after 210 years.
- After completing the Brotherhood of Steel ending, a Brotherhood of Steel knight may be eternally standing guard outside the cave leading to the vault door.
- After gaining access to Vault 81, the vault control panel will be considered an NPC saying normal lines like: "Yeah?" or "Huh?"
- Caravans can sometimes be found outside the vault entrance as it's one of the stops on their route.
- The kids in the classroom may be seen taking the G.O.A.T. but this happens rarely.
- During the pre-War beginning of the game, the news anchor on the TV notes that there are still openings in Vault 81.
- On the left side of the vault door, on the outside, there is a Railsign symbol meaning "Ally."
Vault 81 appears only in Fallout 4.
- PC Playstation 4 Xbox One When first entering the Vault, you may be unable to open the door as the "You cannot do this while in combat" message will appear. This is because the two turrets on the ends of the wall are hostile, although they do not attack. The only way to "see" the hostile turrets is using VATS, since they will also not appear marked on your compass. The turrets are also immortal, which makes all efforts of destroying them to continue futile.[verified]
- The only known way to destroy them is via the KillAll console command, but this will also kill most residents and characters inside. The only known way of resolving this is opening the door while sneaking. (completely hidden, a Stealth Boy is recommended) After, the animation will commence and everything will return to normal, but the turrets will remain hostile and immortal forever.
- Another fix may be to fast traveling from and return to the vault.
- You can also destroy these turrets in VATS using critical hits or using explosions.
- Playstation 4 Xbox One After using the speech check, the main door never opens. Reloading to an earlier save (before the speech check) can fix this.[verified]
- PC Playstation 4 Xbox One The vault security guards will sometimes refer to the male Sole Survivor as a female.[verified]
- PC Playstation 4 Xbox One On the surface, the button in the main elevator will be on the eastern side. While the elevator is in motion, the button will be on the northern side. When inside the vault, the button will be on the western side. This is most noticeable if the elevator is activated in third person.[verified]
- PC Holt Combes will disappear after exiting the vault occasionally this can be fixed by using the elevator and searching again.[verified]
- PC Playstation 4 Xbox One Dr. Penske will give a quest to deliver fertilizer for 25 caps a piece however after agreeing she will give standard dialogue when prompted to talk. [verified]
- PC After finishing the quest Hole in the Wall, Vault Security will refer to you as a woman even if you are a male character saying: "You're a brave woman. I wish we could've handled it ourselves, but no doubt, we'd have gotten eaten alive down here." (see gallery)[verified]
- PC Playstation 4 Xbox One After entering Vault 81, the main elevator you see when you first come in may be non-existent, resulting in an [endless fall under the map] which can easily be escaped by moving forward back onto the floor (Though any companions that happened to follow you will be endlessly falling). Reloading a save, or exiting and entering the vault again should fix it.[verified]
- Playstation 4 Xbox One If access is gained to the vault via Charisma a glitch will occur where you cannot enter the door to the elevator. Calvin and the Overseer will also be unable to open the door. The door or the button to the left of it would show "INACCESSIBLE". To access the door, the player must accept the overseer's exchange by delivering three fusion cores instead of using Charisma. [verified]
- PC Playstation 4 When in the secret Vault 81 the mole rats that come up from the ground freeze in some areas. It also causes them to sprout from the metal roofing of the facility.[verified]
- Playstation 4 Xbox One Part of the wall at the end of the hallway opposite the classroom doesn't load and is a blank space. [verified]
- PC Xbox One After the first interaction with him, Calvin (the man who bought tools), will disappear and end up in the hidden "Vault 81 Holding Cell," which is a door hidden behind the residential area upper hallway wall, between the bathroom on the left of Holt and Alexis' room, and the wall immediately to the left of the security guard in the corridor at the top of the steps leading to the 2nd floor.[verified]
- This can be temporarily resolved by opening console and typing prid 00153855 then moveto player.
- If the holding cell door was opened, go back into the wall, select the door, then type lock 1. Change point of view so the the "Unlocked" message disappears, then look at door again, it should now say "Novice Lock". NPC's will not be able to unlock this and will stay in the halls if they don't have an assigned room.
- Playstation 4 Xbox One There is an invisible footlocker underneath the bunk bed in the same room as the Giddyup Buttercup. [verified]
- PC If player character kills all of the Vault 81 dwellers, leaving only the essential NPCs and all children in the vault alive, and hasn't finished the tour that Austin Engill gave, once the player character exits the vault and returns back, all NPCs in the vault will return back to neutral. When the player character talks to Austin Engill and decided to stop the tour, player character will complete the quest and received EXP despite not finishing the tour and killed almost all the vault residents. Some quests might be still able to start after this happens.[verified]