The oceans define the earth. They cover almost 75% of the planet and hold 97% of its water. Nearly half of the world's population lives within 60 miles of the sea. Scientists say that 10 million to 30 million species of sea life may still be undiscovered.

Under the Sea
Earle, 63, takes fish personally. She has gone on at least 50 diving expeditions and spent more than 6,000 hours under the sea. After one dive she rejoiced that she had met an 18-inch-long shark with glowing green eyes. She claims she once bumped into "a grouper with attitude."

In 1970 she was captain of the first team of women to live beneath the ocean's surface. The five "aquanauts" spent two weeks in an underwater laboratory--a small structure--off the U.S. Virgin Islands.

Since 1979, when she walked freely on the ocean floor 1,250 feet beneath the water's surface, Earle has been known as Her Deepness. She holds the world record for the deepest dive by any human outside a submarine.

Now Earle has a new job: explorer-in-residence for the National Geographic Society. As the leader of a five-year project, Earle will use a zippy new submarine to study the waters of the 12 national marine sanctuaries--underwater areas similar to national parks that are protected by the U.S. government.

Earle feels personal responsibility for the ocean's future and safety. She believes human beings are the first species to be able to have an impact on the entire world.

Threats to the Ocean Earle is terribly concerned that people are polluting and overfishing the ocean. Fishing methods that use trawlers to dredge the ocean floor also destroy underwater habitats. Earle calls the trawlers "bulldozers."

Another threat comes from man-made fertilizers, which wash off fields into streams and eventually into the ocean. This encourages the harmful overgrowth of algae and the spread of toxic germs that can kill fish and cause human health problems. Billions of fish died along the Middle and Southern Atlantic coast of the U.S. in recent years, and pollution is the main suspect.

Earle offers several solutions to these problems. She urges people to take action, to volunteer to clean a beach. She also hopes people will learn as much as they can about how the ocean keeps all of us alive. "Far and away the greatest threat to the ocean, and thus to ourselves, is ignorance," she says. "But we can do something about that."

Earle sits on a rock and stares out at her beloved sea. She claims the key to the earth's future is not to be found among the stars. "The future is here," she says. "This aquatic planet blessed with an ocean."