The MJ12 Ocean Lab, also known as the MJ12 Sea Lab, and MJ12 Sub Base, is a location visited in Deus Ex. As its name implies, the facilities are a coastal and underwater laboratory owned by Majestic 12 and located on the "New" California Coast following the 2030 earthquake that sunk most of southern and baja California.
The Lab was constructed in front of the SoCal SeaWall (a massive concrete wall hundreds of meters tall used to keep the ocean from flooding southwestern America) partially to allow easy sea access and partially to keep the lab secret. JC Denton is sent here by Gary Savage to collect the containment unit schematics for X-51's Universal Constructor following Tiffany Savage's failed attempt to steal the schematics herself. The "Sub Base", the first part of the base, consists of a large complex standing on tall Struts that houses several former X-51 scientists, MJ12 Troopers and Men in Black. This complex leads to a series of heavily guarded catwalks, and eventually to an elevator leading to the Sea floor, where Submarines can be taken to the True Ocean Lab.
The Ocean Labs themselves are in bad shape. A rogue scientist named Ridley, who claimed to be an Illuminati sleeper agent, has sabotaged the base. After detonating several LAMs throughout the base and giving the base a crippling computer virus, much of it is flooded. Most of the Transgenics have broken out of their cages and the Security Systems are malfunctioning, murdering all of the Lab's residents.
After traversing the Ocean labs, JC enters a mining area deep underground, and eventually finds the Universal Constructor repair area. This area is patrolled by one of the few Chiang M5s found in the entire game, but it is the last area visited. After finding the schematics, Bob Page will threaten to launch a nuclear warhead at Vandeberg, prompting JC to leave the base quickly. Once he re-enters the mining area, Walton Simons, accompanied by two frogmen who will attack the player. If JC does not kill Simons, he will reappear later in the game, at Area 51. Following JC's departure, the lab is taken over by X-51 personnel.
- During development, this map was intended to be set on the Moon as a base, but the level was later scrapped.