Icon cut contentThe following is based on Fallout 4 cut content and has not been confirmed by canon sources.

20 Leagues Under the Sea is a cut quest in Fallout 4.

An unused Institute terminal entry (InstM02Terminal2Message) reads:

MS03 Temp Hydroponics MessageEdit


Access: Local. Login: ABinet.
Notes: Routine diagnostic on Courser designate X6-88, all functions nominal.
Access: Local. Login: ABinet.
Notes: More programming work on new AI software update.
Access: Local. Login: ABinet.
Notes: Prototype testing of neural net upgrades.


  • The editor ID and quest name can be found as part of the file name for the quest icon.
  • An unused marker named MS03ResurfaceMarker can be found in the game data.
  • The quest's Pip-Boy animation is the only occurence of a living sea creature.

Behind the scenesEdit

The name of the quest is based on the novel Twenty Thousand Leagues Under the Sea by Jules Verne.