'You leave fear on the surface,' says Dr. Earle

I find the lure of the unknown irresistible," says the indomitable and unsinkable marine botanist Sylvia Earle. At 45, Earle has logged nearly 5,000 hours underwater—including 14 days at one stretch. She has swum with humpback whales. She has explored undersea kelp forests off California. And on Sept. 19, 1979, off Oahu, Hawaii, she descended 1,250 feet under the Pacific, deeper than anyone, man or woman, has ever gone without a tether to the surface.

Wearing a special deep-sea suit to protect her from pressure 35 times greater than that at sea level, the 5'3", 115-pound Earle was lowered to the bottom strapped to the front of a research submarine. She then walked alone for two and a half hours. "There I was, a little human being walking on the ocean floor," she recalls. "I felt like I was an astronaut landing on the moon."

That dive led to another challenge, fearsome in its own way: facing up to the brave but peculiar denizens of the New York-based, 75-year-old Explorers Club. After a 753-618 vote this April to break the club's traditional males-only policy, she and astronaut Kathryn Sullivan became the first women to have membership applications accepted (they're still pending). Sylvia was also one of 10 recipients of the new Lowell Thomas Award (the only woman so honored), joining Carl Sagan, Isaac Asimov and Thomas himself. "Nice comrades," says Earle. She had once scoffed at gender differences among divers, pointing out that "the only thing men can do down there that women can't is grow beards." But she was gentle to the Explorers. "I've always said," she explained, "underwater or on top, men and women are compatible."

Now curator of phycology (study of algae) at the California Academy of Sciences in San Francisco, Earle is better known for her on-camera role in Gentle Giants of the Pacific, a TV documentary on whales, and for her National Geographic articles. Among myriad other ventures in marine conservation, Earle co-founded the nonprofit Ocean Trust Foundation in 1978. She is deeply concerned about ocean pollution and exploitation of underwater resources. Yet she recently okayed a Getty TV commercial that cited her record dive as an example of how "America gains most when individuals have great freedom to pursue personal goals without undue government interference." She says, "What is needed more than law is the development of an ethic. I see nothing wrong with the ad." She donated her honorarium from the campaign to a variety of conservation organizations, including the Ocean Trust Fund.

She also defends her visibility, remarkably high for a scientist. "When I write a scientific treatise, I might reach 100 people," she says. "When the National Geographic covers a project, it communicates about plants and fish and underwater technology to more than 10 million people. And we've shown Gentle Giants to more than 200 million."

Twice divorced (from marine zoologist John Taylor and ichthyologist Giles Mead), Earle has three children, whose ages range from 12 to 20. (Earle says daughter Gale, 12, "claims she loves the water because I was still diving while eight months pregnant.")

Sylvia's now collaborating both romantically and professionally with British engineer Graham Hawkes, 33. He designed the undersea vessel, Wasp, that served as backup for Earle on her deepest foray. His latest submersible, called Deep Hawk—to be tested near the Galápagos Islands late next year—is a clear acrylic sphere fitted with tiny wings to guide its movements. Unlike the suit Earle wore in 1979, which can't go deeper than 2,000 feet and has awkward pincerlike hands, Hawk is a prototype for more advanced diving craft. It can dive to 5,000 feet and is equipped with external manipulators so precise, Earle boasts, "I could write my name with them."

When Earle first prodded him to design such a vessel, Hawkes recalls, "I kept giving sound reasons why she couldn't go to the bottom of the sea—pressure, cold, dark, power problems. Then I realized she wasn't listening to my logical arguments. She was like a stubborn child saying, 'I want to.' I thought she was lovely but single-minded."

Earle spent most of her adolescence in the water, after her engineer father moved his family from a small farm in Gibbstown, N.J. to Dunedin, Fla., on the Gulf of Mexico. She first donned scuba gear in college, graduating in 1955 from Florida State with a major in botany and many zoology courses. The following year, Earle received an M.A. in marine biology from Duke, which 10 years later granted her a doctorate. "I decided to concentrate on botany because I didn't have to kill as many things," she says. "Zoologists spend a lot of time looking at cadavers."

Since her first big trip—a National Science Foundation expedition to the Indian Ocean in 1964—Earle has hardly had a chance to towel off at home in Oakland, Calif. Her projects included the 1970 experiment led by the Interior Department, Tektite II, in which she joined three other women living underwater off the Virgin Islands for 14 days. And she examined underwater plant life growing in Japanese hulks off the Truk Islands in 1975.

The fact that she can't remember any life-threatening incidents hasn't made her overconfident. "I get apprehensive all the time; there's a fear of the unknown whether it's a person, policy or fish," she says. "But you have to leave fear on the surface. When I dive, the main thing is, I'm there, it's beautiful and let's see what I can do."