Canadian astronaut-to-be David Saint-Jacques isn't yet scheduled to go to space, but he is going where few people have voyaged: to one of the world's only underwater bases.

Saint-Jacques will live on the Aquarius undersea laboratory off the coast of Florida for 13 days as part of a NASA mission set to start this week. The U.S. space agency is hoping to feel out what it might be like to land astronauts on an asteroid, and has decided that an underwater environment presents the best way to simulate the experience.

David Saint-Jacques completed astronaut training earlier this year, but his first mission will be to the ocean floor, not space. Emily Chung/CBC

Unlike the moon, asteroids have next to no gravity — an effect similar to working under the ocean.

"The work we're doing here is a very early, pre-engineering assessment of the techniques that might be useful. So we're going to try out a bunch of methods that we can think of to explore an asteroid, and try to maybe rule out those that are not even worth pursuing," Saint-Jacques said in an interview this week.

The underwater lab is several kilometres from Key Largo, Fla., and about 18 metres down. That presents a few complications for the six people who will be living there for nearly two weeks, but nothing as intricate as space travel.

"We'll be staying underwater for so long that we can basically consider all our body fluids completely saturated with nitrogen," said Saint-Jacques, a physician and PhD astrophysicist who hails from Quebec City. "That means that if we need to come up, there's a big procedure involved."

The crew, part of NASA's Extreme Environment Mission Operations, or NEEMO, was supposed to descend Monday. But a tropical storm in the area delayed the project, and they're now looking at starting Thursday.

Saint-Jacques, 41, graduated from NASA's astronaut school a few months ago and is hoping to fly on a space mission in the next decade. It's a world apart from his time as a physician in Northern Quebec, he said.

Click above or here to listen to CBC News senior writer Zach Dubinsky's full interview with Canadian Space Agency astronaut-to-be David Saint-Jacques.