From PEOPLE Magazine Click to enlarge
On her 12th day at sea, over 1,000 miles from land, Mary Crowley swims in 17,000-ft.-deep, cool Pacific water, not far from the Kaisei, her elegant square-rigged ship. The sun is high, the water is gorgeous—except for the clumps of plastic that bob by.

Though the flotsam is disgusting, it confirms that Crowley and her team of six scientists are in the right place. The Kaisei is on a monthlong voyage to the Great Pacific Garbage Patch. "Some people call this the eighth continent," says Crowley of the millions of tons of trash—bags, toys, bottles—spanning an area estimated at twice the size of Texas and caught in a massive clockwise current between the U.S. and Japan. This watery dump (not the only one on Earth, but the largest) has vexed environmentalists since gaining widespread attention a decade ago. Because the area is vast, remote and moving, it has been almost impossible to map, much less eliminate. "We knew there was plastic out there," says Holly Bamford, director of the National Oceanic and Atmospheric Administration marine debris program. But until recently, "we didn't know the concentrations. The numbers have increased, and it is causing some concern."

Some scientists have long believed that cleaning up the Pacific Patch is unfeasible. But Crowley, 63, a Sausalito-based charter-yacht broker who is volunteering her time to Project Kaisei, is determined. Her expedition has received the endorsement of the United Nations, while private and institutional donors footed the $300,000 cost. Ship-side and in dinghies, her team is attempting to gauge the quantity of trash and is testing various collection devices.

Crowley isn't the only one who feels cleanup is important. In the fall, eco-adventurer and TV host David de Rothschild will explore the region in a recycled plastic boat. While some of the garbage—the bulk of it litter from beaches and rivers—washes up on Hawaii and other islands, the majority stays in the water, poisoning marine life, which mistake the smallest bits for plankton. Biologists on board are checking tissue samples to understand the effects.

Not yet near the densest part of the Patch, the Kaisei team spots 400 pieces in the ocean during a one-minute count. What can become of it all? "We're hearing from scientists about turning plastic into fuel," says Crowley. "We've over-garbaged the ocean. But I'm optimistic we can change."