Going deep: Misson 31 aquanauts set to submerge (pictures)

Fabien Cousteau, grandson of famed ocean explorer Jacques Cousteau, and a team of fellow aquanauts on Sunday will dive down to Aquarius Reef Base, an undersea lab 63 feet down in the Florida Keys National Marine Sanctuary. They plan to make the school-bus-size lab their home for 31 days, while exploring the deep and conducting scientific research -- all the while broadcasting the mission live.

Liz Magee, seen here next to Aquarius Reef Base, will be part of the second wave of aquanauts joining the expedition.

Matt Ferraro (left), director of photography, and Cousteau during training for Mission 31.

A monthlong mission takes extensive planning. That includes preparing in case something goes wrong.

"This is a very serious endeavor," Cousteau said in an earlier interview. "Physically you have to be in very good shape. It's very much like going into outer space." In fact, many astronauts become aquanauts at Aquarius to train for space missions.

Aquanaut Grace Young gets some help with her Kirby Morgan diving helmet during training for the mission.

The team has been doing some intensive training leading up to the mission. That includes simulating emergencies.  They don't expect to have to use that training, but it's necessary, Cousteau says.

Outside Aquarius Reef Base, Cousteau tests camera equipment.

Mission 31 aquanauts will use this custom camera housing by Watershot to help capture images underwater during the expedition.

The aquanauts will use Nokia Lumia 1020 smartphones with custom housing by Watershot during their time down below. Nokia is one of the sponsors of the monthlong expedition.