Sea of Tranquility

The Sea of Tranquility is a location on the Moon.

Background
A reference to the Sea of Tranquility appears on a placard in the Museum of Freedom, where it mentions soldiers had fought there to secure America's freedom.

Appearances
The Sea of Tranquility is mentioned only $$

Behind the scenes
The Sea of Tranquility is the English translation of Mare Tranquillitatis, a lunar mare.