This is the Floating Instrument Platform, or FLIP for short. It was developed by the US Navy in the 1960s to study how waves behave under water, as well as water temperature and density, and acoustics beneath the surface of the sea. When doing research that needs to be perfectly still, waves in the ocean will rock you around. Not so with this ship. Because of the potential interference in acoustics caused by a motor or engine, the FLIP has no means of propulsion and must be towed to open water.

When the 335-foot research vessel flips, the crew must stand on the deck. It takes a total of 20 minutes for it to flip from horizontal to vertical and vice versa. The interior of the facility is specially designed to accommodate the FLIP. Bathroom fixtures have been duplicated, and kitchen fixtures have been installed on moving components that allow them to flip with the FLIP.

via U.S. Navy