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MarineLab Undersea Laboratory

MarineLab Undersea Laboratory

The MarineLab Undersea Laboratory was the world's longest continually-operated underwater research facility. Built by the Midshipman of the US Naval Academy as an exercise in ocean engineering, the Undersea Lab has survived hurricanes and, until now, has never moved from its placement in the MRDF lagoon in 1985.

In March 2018, MRDF removed the MarineLab Undersea Laboratory from the lagoon and emplaced it on shore at Key Largo Undersea Park. The habitat will be renovated and restored to its original condition when it was first placed underwater in 1984. It will become an immersive, interactive museum open to the public. Visitors will feel like they are actually in an underwater habitat when they enter the structure, and both static and interactive exhibits will be incorporated into the interior and exterior.

Key Largo is the home of the world's only three underwater laboratories. Scientists have access to FIU's Aquarius facility; recreational divers can visit Jules' Undersea Lodge; and soon, everyone will be able to visit the MarineLab Undersea Laboratory Museum.


MarineLab Undersea Laboratory before submergingConceived in 1970, the MarineLab was originally called the MEDUSA (Midshipmen Engineered and Designed Underwater Studies Apparatus), and provided engineering design and project management experience for several hundred midshippmen over a ten year period. The habitat was developed under the direction of Dr. Neil Monney, at the US Naval Academy in Annapolis, MD. Dr. Monney was the Director of the Oceaneering Department of the Naval Academy.

Although completed in 1980, the habitat was never placed in operation by the Naval Academy. In 1984 Dr. Monney arranged to have the habitat given to Marine Resources Development Foundation, and it was renamed MarineLab. A suitable location was found within John Pennekamp Coral Reef State Park, and agreement was reached with the then-Florida Department of Natural Resources for the use of the site. The habitat and support van were transported to Key Largo and emplaced in 1984. Operations began in June, 1984 with Chris Olstad as On-site Director. Twenty-one 24 hour missions were conducted that summer involving approximately 80 aquanauts.

In 1985, the MarineLab habitat, also called the "Classroom in the Sea," was moved to a permanent site at the Foundation's headquarters in Key Largo, Florida.


The structure is composed of a surplus steel water tank, 16 feet long and 8 feet in diameter. There is a 3 foot diameter observation port at one end of the cylinder, and a 66-inch diameter acrylic observation sphere mounted beneath the cylinder. This acrylic sphere was the test hull for the US Navy Submersible NEMO, which was developed by the Naval Civil Engineering Laboratory, and was designed for submerged operations to 100 feet. Access to the sphere is from inside the laboratory, making it a dry observation area.  

MUL's BubbleCradle and Ballast

The base of the laboratory consists of a cradle and ballast tray constructed from I-beams, angle iron and concrete. Approximately 3.6 tons of ballast are required for the underwater lab.

Internal Layout

Inside the lab are three bunks, one of which can be converted into a work bench.  It also contains a microwave oven, a refrigerator, and a sink. There is a wetroom which contains a shower and portable toilet. The principal access hatch for the lab is also located in the wetroom. A second hatch is located at the opposite end of the lab for emergency exit.

MUL InteriorThe main living and laboratory area is separated from the wetroom to control humidity and to maintain a feeling of normal living accommodations. All framing, partitions and shelving are fabricated from metal and have been coated with an epoxy paint system. The walls of the lab are insulated with a closed-cell, pliable foam insulation of the type used in Navy submarines.

Atmospheric Control, Power & Water

Air is supplied to the lab by a low pressure compressor via an umbilical from a surface support van. The humidity and temperature of the air are controlled, within certain limits, on shore to properly condition the lab environment. Scrubbers are not necessary for removing carbon dioxide from the atmosphere because a sufficient flow of compressed air is maintained to continually flush the laboratory and remove all contaminants.

110 volt AC power is used in the lab for refrigerator, lighting, and microwave oven. Power is provided via the umbilical from the surface, but power for emergency lighting and communications is supplied by 12 volt dry batteries in the lab.

Hot and cold water to the sink and shower are provided via the umbilical from the surface van.

A water level alarm in the entrance hatch signals any decrease in air pressure in the lab. Communications between the laboratory and the support van includes a VHF radio, an intercom, a set of sound powered phones, and closed circuit TV.

Shore Support

Command Van ExteriorThe shore support facility is housed in a 20 foot van located in close proximity to the laboratory. Two low pressure compressors, located in the support van, supply primary and backup air for both the lab and hookah diving hoses. It should be noted that the lab is not equipped with high pressure air. Diving operations will be conducted on the 100 foot hookah rigs. Power to the support van is provided by a commercial 220 volt 3 phase circuit.  A diesel powered generator is housed outside the support van for emergency power.

Command Van InteriorAdditionally, the support van houses the VHF radio-intercom systems, TV monitors, bunks and a desk for the Operations Director or watch officer, first aid supplies, dive logs, emergency stand-by diving equipment, spare parts, and tools.

The umbilical carries: (1) two low pressure air supply hoses (2) communications cables for the intercom, sound-powered phone, and TV camera (3) 110 volt AC power supply (4) 12 volt DC power supply for outside lighting, and (5) hot and cold water supply hoses.

In order to provide MarineLab participants with an interesting location for the conducting of scientific observations and yet remain within the restrictions imposed by safety considerations (no decompression, protected from open ocean), a site was selected within a mangrove lagoon. This site is in 27 feet of water and away from marina access channels.

The underwater lab and the support vans causes minimum impact on the environment. All participants are briefed on the environmental impact prior to each mission. The Operations Director ensures that a site clean-up and inspection are conducted at the completion of each mission.