|Far Harbor main quest: Where You Belong|
|Talk to the leader of Acadia.|
|Leads to: Acadian Ideals|
|Talk to Kasumi Nakano.|
|Hack Faraday's terminal.||Gain access to the storage room.||Talk to DiMA.|
|Obtain Faraday's program.|
|Report back to Kasumi.|
|Reward: 500 XP|
|Leads to: Best Left Forgotten|
Old Longfellow leads the Sole Survivor to Acadia and gives them a reward. The Sole Survivor enters the settlement, where its leader, an old synth by the name of DiMA, greets the player character and informs them that Kasumi is indeed there.
If Nick Valentine is brought along as a companion, it is revealed that DiMA and Nick are technically "brothers," as they were the first two prototypes of the Institute's attempts to give a machine free will and thought. DiMA explains that he was the one who freed Nick from the Institute, though having done so over a century ago, Nick's memory of the event had worn away, though DiMA bears no regret for this.
The Sole Survivor is directed to Kasumi's location in the basement of the settlement and is extended an invitation to explore the colony, and meet the fellow founders, Faraday and Chase; thus beginning the Acadian Ideals quest.
Upon traveling to the basement, Kasumi affirms her belief that she is a synth, though the Sole Survivor may try to change her mind. She then confesses that she also believes there's a secret behind Acadia, and presents three options for finding it out: talking to DiMA, hacking Faraday's terminal, or eavesdropping on their meeting by hiding in a storage closet. Choosing any of the methods result in the truth being revealed: DiMA gave an old nuclear submarine to the Children of Atom as a home base, now known as "The Nucleus." If one decides to talk to DiMA, a speech check will need to be passed.
The vessel is also where DiMA stored his old memory files, putting the two factions (the Children of Atom and the Harbormen) on the brink of war if they're discovered. Now, the only options are to either talk to DiMA or steal the program from Faraday's desk, in the room to the right of the main chamber. Taking the program takes the player character back to Kasumi, who speculates that DiMA may know more, but leaves it up to the player character to figure that out, ending the quest and starting the quest Best Left Forgotten.
- It is possible to get up to three likes with Nick Valentine if the Sole Survivor is a member of both the Institute and the Railroad.
- Nick will dislike choosing "I'm in the Brotherhood" then "Give Acadia a chance." But choosing this for Curie will result in her liking it.
- If the storage room has been opened before talking to Kasumi, choosing to eavesdrop on the meeting will result in the Sole Survivor saying that they have opened the door already, instead of finding a way to open it.
- If eavesdropping, passing a speech check with Cog reveals he lost a key to the storage closet. It is in the upper walkway of Dima's observatory on a table at the very end of the walkway. The key is available even without the speech check
- If traveling with Danse, he will hate it if one chooses "I'm in the brotherhood" then "Give Acadia a chance."
- Using the stealth option can leave the player character stuck in the Stealth Boy effect. The Pip-Boy is not visible, presenting an unplayable situation.[verified]
- From the Bethesda customer service website: We are investigating reports that some players are turning invisible after eavesdropping on DiMA in Far Harbor. If you experience this issue, you should completely exit out of the game and restart. If playing on console, we also recommend rebooting your Xbox One or PlayStation 4.