The only underwater laboratory in the world is located in the Florida Keys National Marine Sanctuary. This underwater lab is located more than three miles offshore at a depth of 63 feet. It is attached to a base plate which secures the laboratory about 13 feet off the bottom of the sea. The laboratory is known as Aquarius and is owned as a joint venture between the National Oceanic and Atmospheric Administration (NOAA) and the University of North Carolina.

Scientists live and work inside the habitat when they are not exploring outside on the adjacent coral reefs. Entry to the module is through the wet porch, which contains an open moon pool, dive equipment storage areas, hot water heater, and shower. There are two main compartments in the Aquarius module. The entry lock contains space for computers and experiments, power equipment, life support controls, small view ports, and bathroom facilities. The largest living space is in the main lock which is designed for a six-person crew. This area has computer work stations, two large view ports, and kitchen facilities. The kitchen facilities include a microwave, instant hot water dispenser, refrigerator, sink, dining, and work areas. The main lock also contains life support controls, so both the entry and main locks can be independently pressurized.

Since the early 1990s scientists have lived in the lab and explored the deep ocean in missions that can extend up to ten days in length. The laboratory is at a depth which requires 17 hours of depressurization for divers who stay down for more than a couple of hours. Scientists use a special technique called saturation diving. Saturation diving refers to a condition involving a diver who is underwater for several hours. After this time, the divers blood becomes saturated with gases. The diver will require the same amount of time for depressurization whenever he or she comes up to the surface.