A Life Aquatic.

Byline: editor: Sarah Brown

Ocean adventuress Celine Cousteau embarks on a noteworthy new mission: fighting your fine lines and wrinkles. Catherine Piercy reports.

Fresh off a five-week stint sailing along the coast of Queensland, Australia, Celine Cousteau--granddaughter of legendary sea adventurer Jacques, daughter of modern-day ocean pioneer Jean-Michel, and a buzz-worthy aquatic thrill-seeker in her own right--has zipped halfway around the world to meet me in Manhattan for a spin through the American Museum of Natural History's "Water: H2O=Life" exhibit. What was the petite brunette doing in Australia? "Oh, catching and tagging sharks," she says cheerfully as we head inside. "Grey nurse, bull, reef, tiger--gorgeous." Of course.

It is this mix of passion and fearlessness that caught the attention of Swiss skin-care company La Prairie, which snapped up the 35-year-old Cousteau as the face (and voice) for its covetable Advanced Marine Biology collection. Infused with antioxidant sea parsley, mineral-rich seaweed, and collagen-stimulating red algae extract, treatments like the refreshing gel-cream use innovatively land-harvested plants (the same kind found wild in the sea, but cultivated in a lab near Nova Scotia) in an effort to protect fragile aquatic ecosystems. The Tonic is a blue, yellow, and green triple-phase liquid that, when shaken, transforms into a three-in-one line-fighting, face-brightening, and oxygenating lotion; the peptide-packed Night Solution stimulates the skin's own healing mechanisms from exposure to environmental aggressors like, in Cousteau's case, ocean sun and wind.

Cousteau spends six months of the year scaling glaciers, camping out along the Amazon River, and swimming with sharks

Cousteau--who spends six months of the year scaling glaciers, camping out along the Amazon River, and swimming with sharks for documentaries for the Discovery Channel and PBS's Jean-Michel Cousteau's Ocean Adventures series--has been passionate about ocean ecology since she was a child sailing around the world aboard the Calypso, "an old minesweeper leased by my grandfather from the Guinness family for a symbolic one franc a year." At the age of nine, she took her first underwater journey, scuba diving with grandfather Jacques off the coast of Monaco. "There was no fear involved," she recalls. "I remember him saying, 'OK, Celine, this is your mask, this is your ...