An elaborate cave system stretching below the southwestern end of the Appalachians, the Deep was chosen by communist infiltrators as the site for Motherlode interception operations, as well as a site for a listening post for nearby areas. Maintaining strict secrecy, including standing orders to shoot anyone without clearance, it escaped notice even with the Whitespring bunker next door. Sealed after the Great War, the facility remains crewed by communist holdouts.
While their exact mission is uncertain, by the nature of their location and requirement of a Motherlode drill, it appears their target was the Whitespring bunker.
Upon entering the cave, there are cave crickets along the narrow passages leading down to a body of toxic water. At the end of the water is the body of James Addison, a diver with the holotape President's eyes ONLY. One must swim across and down under the water's surface to the other side of the cave, upon which a set of passageways leads to brightly colored flora including fever blossoms, kaleidopore, and starlight creeper bushes. Small pieces of material fall from the ceiling, and in the middle of the flora chamber is the body of a creature.
Further inside the tunnels, there is a small opening allowing one to see a base of communist soldiers. Heading further down, one will reach a T-intersection. Going straight down will lead to an exit next to the Whitespring. On the left, there is a walkway on the base. The walkway has a few soldiers and Liberators wielding energy weapons. The communists surround the island-like base, which has a moat of ultracite. Two to three soldiers will be on the roof of the base, one with a missile launcher, which can be accessed by stairs on the side.
In the interior of the base, there are three levels including a basement, a first floor, and a second floor. Communist soldiers and two commanders in power armor are inside or nearby the building. At the bottom of the base is an auxiliary control room door on the left. The other door (locked) has a chamber where the Motherlode will appear and will bring the player character to the Mire or several areas within the Savage Divide. The PRC Motherlode access key is found on the commander's body.
- President's eyes ONLY - Holotape, found on the corpse of a diver just before the toxic water past the entrance tunnels.
- PRC Motherlode access key - Key, found on the corpse of a communist commander inside the main facility.
- Potential Vault-Tec bobblehead - On the top floor of the main facility, on a console along the southeast wall, near a steamer trunk.
- Two potential armor mod plans:
- On the top floor of the main facility, on a middle bunkbed, facing the eastern wall.
- On the top floor of the main facility, on a green container, facing the southwestern wall.
- Mini nuke - On the top floor of the main facility, on the edge of a green container facing the southern wall.
- 18 starlight creeper bushes:
- 13 around the base.
- Five next to the western entrance to the caves.
- 24 fever blossom plants along the cave passageways and near the main building.
Behind the scenes