
It is impossible to reconstruct the complete storyline for Vault 120 and 20 Leagues Under the Sea due to the absence of dialogues, quests, and other essentials. The level geometry and scenery are mostly intact and can be rendered using fo76-utils, allowing for reconstructing the flow of the location.
00004CCA (Vault 120, a generic airlock, zCUTUnusedVault120AirlockCOPY0000). 00004D4C (Vault 120, later referred to as "generators" to avoid confusion, zCUTUnusedVault12002COPY0000),. However, a complete level is included in the files of Fallout 76, at records: The cells of Vault 120 do not exist in the game files of Fallout 4. The giant squid would have been the vault's overseer. The adventure there would involve a sentient giant squid contained inside the Vault, and the Vault itself would be inspired by BioShock. It would have been involved in the cut quest 20 Leagues Under the Sea.
Vault 120 is a cut Vault-Tec Vault located off the Atlantic coast of Massachusetts, underwater in the Commonwealth. The following is based on Fallout 4 cut content.