When your grandfather is Jacques-Yves Cousteau, and you spent your childhood on the fabled research vessel Calypso, perhaps it’s not surprising that you started scuba diving at age 4. Or that you piloted a 14-foot shark-shaped submarine of your own dreamt-up design, swimming among great whites for “Mind of the Demon,” a CBS television special. Or most recently, that you spent a month on the seafloor in the NOAA Aquarius Reef Base off Key Largo, Florida. This is the life of filmmaker and ocean explorer Fabien Cousteau.

Cousteau expects to release a documentary about Mission 31 this November at the BLUE Ocean Film Fest in St. Petersburg, Florida. We spoke to him about the experience, what happens to your taste buds underwater and an encounter with a 600-pound grouper.

Cousteau leaves the habitat for a research mission © Kip Evans

Even your sister called you crazy for building Troy, the shark-sub (pictured above).

The comic book Tintin was my inspiration. I wanted to make a sub as stealthy and realistic as possible, so I could see great whites’ natural behavior.

You dove in it for four hours. Why?

Diving in it at night was one of the riskiest things I ever did, but you have to push the envelope if you want to know more. Every time I got into that shark-sub, something could have gone wrong. But I wasn’t worried about the sharks – only human error with the machine.

Cousteau in front of the Aquarius Habitat © KipEvansMission

You just logged 31 consecutive days underwater at 60 feet. What was the wildest encounter?

We were actually in the habitat sleeping when one of our cameras captured a 600-pound goliath grouper making a booming sound, and then it bit a four-foot barracuda. Scales went flying. I’ve never seen aggressive behavior like that from a grouper before. And while we were diving, we saw massive, swirling clouds of plankton blooming at night. They looked like tornadoes and snowstorms.

Most people will never get the chance to live underwater. Sounds like the stuff of science-fiction.

It was. So many of the small, everyday things differed vastly. For example, you can’t whistle down there. Your hair grows so much faster. And the air was syrupy – it’s very hard to breathe at three atmospheres. But thanks to that underwater research station, the only one in the world like it, we could scuba dive between six and 12 hours every day. The scientists on our team collected three years’ worth of data in those 31 days.

Cousteau, in the underwater habitat © Kip Evans

Were you ever scared?

Only of the long-term effects. My sense of taste went dull – so much so that I had to put hot sauce on everything, and I’m not a hot-sauce person. I was afraid I’d lost my taste buds forever. Luckily, they came back.

You’re known for shaking things up in the underwater community.

Everyone is so afraid of new technology and trying new things. With a few exceptions, we are still using the technologies my grandfather invented 70 years ago.

Cousteau at the 'Plant a Fish' sea turtle project © Kip Evans

Where do you think diving is still lagging?