The Sea of Tranquility is mentioned only in Fallout 4.
Behind the scenes
The Sea of Tranquility is the English translation of Mare Tranquillitatis, a lunar mare.
- Placard in the Museum of Freedom: "This mural commemorates the many sacrifices of the brave men and women of the United States Armed Forces. From Lexington and Concord to the shores of Iwo Jima, from the Sea of Tranquility to the Anchorage Front Line, Americans have fought and died through the ages to secure our nation’s freedom. May their sacrifices remind us all that freedom is a privilege afforded to the many, yet hard won by a noble few."