Backpacker brigade

Under a broiling afternoon sun, a work crew rakes through the debris-choked riverbank. Each piece of refuse - tree stumps, broken bricks, shards of glass - is tossed into a wheelbarrow or carried by hand to a chest-high pile.

Sweat clings to the bikini-clad back of Belgian advertising executive Greet Wachters as she hacks at the soil. Nearby, a deserted beach offers a tantalizing respite from the work at hand, but Ms. Wachters barely misses a beat as she bends to her task. "It's hard to imagine how much more we have to go. You get the impression that we're doing nothing. But every bit helps," she says. Her husband, Stef Selfslagh, leans on his shovel for a moment and smiles. "As a kid I always tried to get out of doing any hard work. Now I'm volunteering for it."

This young couple from Antwerp are part of a grass-roots backpacker army that has sprung into action to rescue Thailand's Phi Phi Island from post-tsunami oblivion. Alerted by word of mouth, e-mails, and handwritten messages, they arrive primed for action. Some work for a day and move on; others rewrite holiday plans and dig in for the long haul.

"I've seen people come over to the island for four hours, work for 3-1/2 hours, then get back on the ferry dirty and tired, but happy. Why? Because they just cleared part of a street," says Dion Wells, a sales manager from Minneapolis who left his job in January to volunteer.

At least 700 people died and countless buildings were leveled when three giant waves swept tiny Phi Phi on Dec. 26. Survivors were evacuated to the mainland, and residents were told not to return until the government had rezoned the island. But some defied the order and went back, determined to rebuild their businesses amid the wreckage, even if it means working in a legal gray area.

A handful of foreign longtime residents pitched in, and the first store reopened in January. As word got out, volunteers began trickling in. A Dutch-run charity raised money to buy tools. Soon there were nightly meetings to allocate tasks and assign workers. A team of volunteer divers began dredging the bay by hand, assisted by Thai boatmen.

Suddenly Phi Phi was back in business, and a group of bronzed backpackers had found a cause. By mid-May, around 2,000 had contributed time through the Hi Phi Phi volunteer program (www.hiphiphi.com), with daily attendance averaging 100 or more. The resulting buzz has prompted hotels and restaurants to reopen their doors, which in turn has encouraged more day-trippers to visit.

Most volunteers come to lend a hand in order to give something back to Thailand, a longtime favorite among budget travelers.

"This is so exciting and rewarding. I feel like I'm taking something much more real away from my trip than drinking Mai Tais for a month," says Zach Heeter, a pre-med student from Austin, Texas,as he takes a break from bricklaying.

Some participants say they tried unsuccessfully to volunteer in other tsunami-stricken countries like Indonesia before going to Phi Phi. Once here, they are quickly drawn into the community spirit and received enthusiastically by Thai islanders grateful for their labor and spending power.

"I like the backpackers; they're so kind. Without them, we couldn't walk through the streets," says Kwan Kingsaiyuth, a local resident.

Each morning, Hi Phi Phi organizers take newcomers on a tour to point out the tsunami damage and talk up their projects. Much of the island's tourist infrastructure is crammed onto a narrow sandbar, which divides two crescent-shaped bays hemmed in by jungle-clad limestone peaks. Until the tsunami struck, neither bay was visible from the other side through the dense tangle of buildings. Some stretches are now scoured bare.

Down at the beach, Elodie Martin eyes the contents of a net of garbage pulled from the seabed. Among the twisted metal and concrete chunks are unopened energy drinks, CDs, a broken fan. Ms. Martin, a beer exporter from Paris, ticks off items on a waterproof clipboard. About 100 tons have been dredged since February.

Divers often find foreign identity cards, which are passed to embassies tracing missing nationals. They retrieved a corpse in April and sent it to the mainland for identification. Martin, who has volunteered for a month, says that finding photos of smiling vacationers can be jarring. "Each time, you stop and think again about what happened here," she says.

In the evening, the action shifts to Carlito's, an open-air bar. At 7 p.m., a DVD of "The Simpsons" is paused, and John Heike climbs onto the bar to start the meeting. First up is a cheer for workers on the newly completed medical center. Then Mr. Heike, a British diving instructor and long-term resident, recaps other recent successes. "It looked impossible. It was insane, yeah? But it snowballed. You guys made it happen, yeah!"

He asks for volunteers for the next day's projects, including the riverbank cleanup. Someone asks for a work description. "Dirty!" cackles Heike. "But important. Very important job." After a little cajoling, more people raise their hands, and Heike moves on to introduce "Mr. Fuji," a store owner who has come to address the crowd. In hesitant English, the bespectacled Thai man thanks the foreigners for helping his community, raising the biggest cheer of the night.

As the meeting ends, the young backpackers head off to the bars and restaurants for another night of revelry. "Work hard, party hard," declares Nino Wright, a volunteer from Leeds, England. "Go out at night and spread your money around."