Immediately prior to the bombs falling, two individuals found themselves in the mine; Luann and George. They listened as an automated system within the mine warned them of incoming nuclear strikes. Luann wanted to stay, but George wanted to leave. It is unclear whether they survived, however it is likely the mine sealed them inside, as this is how the player character finds it upon arrival. Their presumed last moments are recorded on a holotape found on the mine system terminal deep within the mine.
Just north of the location is a small structure with minor loot inside. The entrance to the mine features a number of parked vehicles and a gantry used to unload ores from mining carts. There is an elevated pod to the left of the entrance containing more minor loot and a few locked explosives crates. To the east of the entrance is another shed with minor loot. To the left and right of the entrance are two claim token exchange terminals, which can be used to redeem claim tokens for prizes.
Mine recorder tape - 10.23.77 - Holotape, on the mine system terminal.
Abandoned mine site Kittery appears only in Fallout 76.