20 Leagues Under the Sea

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

Quick walkthrough
After the passing the Alien in the Cave, you have to take 14 steps to the left. wait until travis mentions something about vault 81. You have to quickly travel to the vault or it will not work.

Behind the scenes
This quest's name is a reference to the 1954 movie and the 1870 book by Jules Verne 20,000 Leagues Under the Sea.