It is not a wreck or something from outer space. Its name is Aquarius, and it sits at 20 meters below surface, next to the coral reefs in the Florida Keys National Marine Sanctuary. It is the only undersea laboratory in the world where scientists and NASA astronauts can live for up to two weeks at the time.

Otto Rutten, is the Associate Director of the National Undersea Research Center. “Aquarius is designed to facilitate undersea research, coral reef research specifically,' said Mr. Rutten, 'to allow scientists to greatly extend the amount of bottom time that they have by utilizing a technique called saturation diving, so they can get from eight to nine hours a day at depths up to 36 meters.”

People cannot work for long at great depths underwater if they have to dive and return to the surface in one trip: much of the time has to be spent decompressing while on the way up, to get rid of the nitrogen that builds up in the body while it is subjected to the extra atmospheric pressure of deep water.

Staying in deep water is the solution; Aquarius is the way to do it. The only way to get to it is by diving, and its main 'door' is called 'the wet porch'. Once inside, you can get rid of your diving equipment, take a fresh shower, get dry, and move in. Aquarius is only 13 meters long by 3 meters in diameter, and can accommodate a maximum of six people at the time.

Jim Backley, Aquarius Operations Manager says that there is only one mission per month: five days of training, 10 days of actual work and then a maintenance period. 'We trained these people that they cannot come to the surface. We take their mask off them and make them swim 20 or 30 minutes following a line. So if they ever lose their mask, they don't go to the surface, they can find their way back to a travel line, so they can find their way back to the habitat.'

Saturation diving allows divers to stay a long time at great depths, but when they want to return to the surface, they have to go through more than 16 hours of decompression inside the habitat. The Aquarius habitat is under strict safety codes.

Keeping humidity and bacteria out of the living area is difficult, and maintenance of the outside structure is a constant challenge. For example, a barracuda, among many other creatures, has adopted Aquarius as its permanent residence.

Jim Backley explains, 'The inside is rough, the outside is what I called a maintenance nightmare, because you have to keep on it on a daily basis.'

On the surface, the Aquarius support team is always on the run: cleaning, reattaching, fixing or keeping a watchful eye on the habitat and its visitors. Floating on top of Aquarius is the Life Support Buoy, or LSB, that not only supplies air and power to Aquarius but also all the communication lines to the habitat.

Five and a half kilometers away is the shore-based mission control center in Key Largo. Here is all the support needed for Aquarius. But Aquarius has proven to be good not only for marine research. For NASA, the National Aeronautics and Space Administration, Aquarius is a perfect place to train future astronauts.

The extreme environmental conditions, the enclose living space; the different pressure and the isolation resemble outer space. 'Other than going into space, this is the next best thing that they have,' said Director Rutten. 'So there is no way to duplicate this, other than Aquarius.'

The next generation of underwater laboratories will build upon the successes and experience of Aquarius.