AGE: 38
HOMETOWN: Paris

LATEST ADVENTURE: The grandson of legendary oceanographer Jacques Cousteau is currently following in the late explorer's foot—well, flipper—steps on his father's new PBS series Jean-Michel Cousteau: Ocean Adventures.

• GROWING UP COUSTEAU
A diver from age 4, Fabien recalls that "one of my first jobs was scrubbing the barnacles" off his grandfather's boat Calypso. On a family expedition to Papua New Guinea when he was 7, "We got lost—there was a lot of concern," he says. "When it is just you and the sea, you realize how insignificant a human being is and how powerful nature is." He's not alone on his Adventures; he and his dad are joined by his sister Celine, 34.

• THE SHARK WHISPERER
To study great whites for a recent documentary, Cousteau built a $100,000, 14-ft. submarine shaped like a shark. "The idea was to get close to them by pretending to be one of them," he says. "The shark-sub was completely noiseless and rolled its eyes and puffed its gills. A lot of people thought it was superkooky—they looked at me like I was pitching 2001: A Space Odyssey. "

• ALL CREATURES GREAT AND SMALL
"I could never choose a favorite animal, there are so many cool ones," says Cousteau. "Obviously I like sharks. I love octopus, and mantis shrimp are fascinating." Back on land the single adventurer admits there's one animal that puzzles him: His shepherd mix Heidi. "She's scared of phone booths," Cousteau says. Alas, she's no better at sea. "When I go underwater, she paces and barks, so she can't come on boats."