SHE LOOKS LIKE ANY OTHER TRIM AND tawny 20-year-old in a pink bikini as she relaxes in a floating chair on the turquoise waters off the Florida Keys. But then, with one last great gulp of air, fashion model Mehgan Heaney-Grier dives in and starts a slow descent—to 50 feet, 60 feet, then 70, all without an air tank. The ocean begins to grow cold and dark, and the water pressure tightens around her like a vise, and still Heaney-Grier keeps sinking.

She's not the only one holding her breath: A team of trainers, physicians and even her parents are waiting in boats above to see if Heaney-Grier can set a new American free-diving record. Free diving? That's the nascent sport where you strap on weights, take a really deep breath and plunge, with only the air you can hold in your lungs, to depths of 100 feet and more. Then comes the hard part: not blacking out from a lack of oxygen while kicking your way back up. On this Aug. 25 dive at the Looe Key National Marine Sanctuary off Little Torch Key, Heaney-Grier finally reaches 165 feet—10 feet deeper than her previous record, set last October—before turning around. One minute and 58 seconds after going under, she breaks the surface and her old record. "Free diving," explains the exuberant Heaney-Grier, "feels just like you're sinking in a big glass of water."

Hardly an activity that is likely to land her on a box of Wheaties anytime soon, but so what? "She has a natural zest for being underwater," says Tec Clark, a scuba expert who officiated her record-setting dive (Cuban divers hold the world records for women, at 204 feet, 6 inches, and men, at 239 feet). Mehgan's greatest challenge, though, will be drawing attention to a sport that has about 10 active competitors worldwide. "But right now," says her boyfriend and cotrainer Mark Rackley, 30, "our main goal is to have enough money to keep doing it."

Heaney-Grier, who has small endorsement deals with two diving-equipment companies, makes about $25,000 a year as a part-time model, while Rackley runs an underwater videography business and spearfishes on the side. They share their modest, two-bedroom home on Little Torch Key with her cotrainer Manny Puig, 43, who helps out with income from his job handling animals on movie sets. "We're living paycheck to paycheck," says Heaney-Grier. Adds Rackley: "We eat a lot of fish and lobster I get right off the dock."

If it all sounds a bit like a Jimmy Buffett song come to life, that's okay with Heaney-Grier's parents, who serve as safety divers on her record attempts. "It was a little radical," concedes her mother, Renee, 44, a nurse practitioner, of her daughter's choice of sport. "But she's like a dog with a bone. She will not let it go." Growing up in Minnesota, Mehgan was a tomboy more interested in climbing trees than in aquatics. But then her parents divorced in 1983, and, five years later, Renee married Nelson Heaney and moved to the Florida Keys, where they run a cottage-building business. Heaney-Grier took to the water like, well, a fish: She spent most of one sailing trip hanging onto a rope off the boat. "I crossed the entire Gulf Stream that way," she says. "I was like a lure."

She also proved a natural at modeling, which she started at 14. But when Mehgan fell in with the wrong crowd at Key West High School, sneaking out at night and coming home late, her mother sent her to Minnesota to live with her father, Bill Grier, a power company lobbyist, for two years. After she moved back to Florida in 1995, a friend introduced her to Rackley, and she moved in with him six months later.

She discovered her capacity for deep diving on a 1995 spear fishing trip and reached 120 feet on her first formal dive. "Going down, it's technique," says Heaney-Grier, who works on drawing more oxygen with her predive breaths. "Coming up, it's determination and heart." Blackouts are a big concern. "Or you could burst an eardrum," says Puig, "and not know which way is up."

So far that hasn't happened to Heaney-Grier, who actually enjoys that breathless rush. "It's like that scene in Willy Wonka, where all the kids are floating up in that room," she says. "That's what it's like when I dive. I just go, 'Wow, what a great feeling.' "

ALEX TRESNIOWSKI
MARISA SALCINES on Little Torch Key

  • Contributors:
  • Marisa Salcines.