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.
  • This would likely take place in an underwater vault as untextured assets can be found in the Creation Kit of both an underwater vault window (VltSquidWindow01) and an underwater vault door (VltLGDoorMarine01) can be found.

Behind the scenesEdit

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