The USS Thomas A. Edison was an Ethan Allen-class ballistic missile submarine in the service of the United States Navy from 1961 until 1983. Although submarines, especially boomers, are supposed to prize silence, the Edison was built with a fully functional piano that remained in use throughout the boat's service.
The Naval Submarine League reports that Steinway and Sons made the custom upright piano for the Navy, which installed the huge instrument during the submarine's construction. Crew members who knew how to play it did so and the piano was often the centerpiece of musical performances conducted by the crew.
The piano was removed when the Edison was scrapped. Veterans of the boat rescued the piano from destruction and arranged for its restoration. It's now in the Steinway and Sons Museum in New York.
-via U.S. Naval Institute