NASA astronauts and a Cincinnati doctor are living and working under the ocean this month to test space medicine concepts and moon-walking techniques.

Canadian astronaut Dave Williams is leading the 18-day undersea mission that ends Thursday at the National Oceanic and Atmospheric Administration’s Aquarius Underwater Laboratory off the Florida coast.

NASA astronauts Nicole Stott and Ron Garan, along with Dr. Tim Broderick of the University of Cincinnati Medical Center, round out the crew.

During the mission, called the NASA Extreme Environment Mission Operations project, remote health care procedures are tested on a patient simulator. NASA said such new long distance medical care procedures as telemonitoring and telerobotic surgery may help maintain the health of spacefarers.

The techniques simulated in Aquarius might one day be used to respond to emergencies aboard the International Space Station, or on the moon or Mars, officials said.

Aquarius is the world’s only underwater research facility dedicated to science. It’s located beneath 62 feet of water at the base of a coral reef off the Florida Keys.

One such space analogue to the International Space Station is an "inner space" station called Aquarius, the world’s only undersea laboratory dedicated to marine science and education.

Aquarius operates 4.5 km off the shores of Key Largo, Florida. The underwater laboratory is deployed next to deep coral reefs, 20 meters beneath the surface. As in its outer space counterpart, "aquanauts" explore and investigate an environment hostile to human habitation. Aquarius provides life support systems that allow scientists to live and work underwater, in reasonably comfortable living quarters, with sophisticated research capabilities, including on-site access to science equipment, computers and the Internet.