Scientists have built a lab 62 feet under the sea, but they aren't using it to explore the ocean

If you want to see how astronauts will mine the Moon, anchor an asteroid, or drive rovers on Mars, then look no further than the NASA Extreme Environment Mission Operations, or NEEMO.

NEEMO is the only undersea research station in the world, and astronaut crews have been training with it ever since the facility was first established in 2001.

Resting on the Atlantic ocean’s seafloor, 62 feet below the surface and 3.5 miles off the coastlines of Key Largo, Florida, NEEMO offers astronauts the closest environment to outer space they can get without strapping themselves to a rocket.

When they’re under the sea, these astronauts train for NASA’s most prestigious upcoming missions — in some sense, you need to learn to be an aquanaut before you can become an astronaut.

Here are some of the incredible things these sea-faring explorers do while they’re getting they’re feet wet for space.

First thing's first: The aquanauts have to get to their undersea station. They do this, naturally, by plunging into the Atlantic.

As they approach their new home, each astronaut crew will see the main base, called Aquarius, loom into view through the clear-blue waters.

Aquarius only has enough room to accommodate up to 7 people at a time and each mission lasts no longer than 3 weeks. Shown here are four members of the NEEMO 10 crew who stayed from July 22 through 28 in 2006.

This photo shows NEEMO 10 crewmembers they reach Aquarius. From front to back are Karen Kohanowich, deputy director of NOAA's Undersea Research Program, Silver Spring, Md.; Japan Aerospace Exploration Agency (JAXA) astronaut/aquanaut Koichi Wakata; and NASA astronaut/aquanauts Karen L. Nyberg and Andrew J. Feustel.

To reduce the risk of decompression sickness when they return to the surface, the aquanauts practice saturation diving -- a technique that limits the number fo decompressions they complete, which reduces the potentially fatal risks that come with decompression sickness.

Unlike the crustacean-crusted outer walls of the station, the inside is clean. It includes a series of peep holes so the crew can enjoy the many fish that swim by. Or maybe it's the fish enjoying the humans.

NEEMO offers the closest environment to space because of the buoyancy we experience while under water. Therefore, working under water is more like working on the Moon or another low-gravity environment than on Earth.

Moreover, NEEMO includes confined living quarters surrounded by an environment that is lethal to humans without the proper equipment, like oxygen supplies. That's why astronauts sometimes train here before reaching the International Space Station. Scott Kelly, for example, is now serving a year aboard the ISS, but trained on two NEEMO missions beforehand.

Here's a tour of the main room in Aquarius. This room includes the crew's dining table, kitchen, work site, electronics, and bunk beds.

Most of the crew members' time is spent outside of Aquarius training for future space missions. Here a crew member climbs a ramp to simulate tasks that would involve similar structures on the lunar surface.

Shown here is the 'door' to Aquarius where crew members enter and exit. It's completely open, so they can come and leave whenever they want. No need to pressurize their suits like astronauts do before a spacewalk.

If NASA brings an asteroid into orbit around the Moon, like it plans to, astronauts might be sent to explore the surface. Because gravity is so weak on an asteroid, they will have to anchor themselves to the surface, which is what this crew member is practicing here:

More information on this is provided in a NASA press release.

In addition to testing humans, NASA's also testing robots with NEEMO. Meet 'Scuttle', a remotely operated vehicle, that crew members practice driving around on the seafloor to test the bot's stability and manoeuvrability.

When it comes to training for future space missions, the huge advantage NEEMO has over the International Space Station is that astronauts can actually adjust how heavy they would feel on different moons or planets. Climbing a ladder on the Moon, for example, will be easier than on Mars.

They do this by attaching weights to their sea suits. The more weights they add, the faster they are pulled down to the seafloor and the closer the environment resembles a large planet with a relatively strong gravitational pull, like Mars.

When humans finally do return to the Moon or reach Mars for the first time, we're going to want to mine it for resources, and that involves some digging. Here, a now-former NASA astronaut, José Moreno Hernández, tests out a shovel.

Crew members also practice building structures that tests their dexterity, which is crucial for spacewalk missions. One astronaut noted 'we had a bit of sand get in our bag of bolts. It makes you appreciate the cleanliness of space. We managed to get the structure put together nicely, and then a large barracuda swam into it as if to inspect it.'

Astronauts are even practicing how they will board an ascent vehicle that will transport them back to Earth from wherever they're stationed: the Moon, Mars, or an asteroid. Shown here is a mock up of an ascent vehicle.

Aquarius isn't just used to train astronauts. The station and its surrounding reef are at the heart of a research program, headed by the Florida International University, which is committed to the study and preservation of marine ecosystems worldwide.

Because NEEMO is located in the midst of a natural habitat, each crew is susceptible to nature's furry. Case in point, in 2011 the path of Hurricane Rina forced the crew of the 15th NEEMO mission to end earlier than planned.

Since 2001, there have been 19 total NEEMO missions, which included astronauts, engineers, and marine biologists from all over the world.

While astronauts are busy preparing for Mars here on Earth, satellites are snapping photos of the Martian surface. Check out these:

Business Insider Emails & Alerts

Site highlights each day to your inbox.

Follow Business Insider Australia on Facebook, Twitter, LinkedIn, and Instagram.