MOUNT PINATUBO, Philippines — Nearly 10 years after Mount Pinatubo erupted in one of the past century's most violent volcanic events, tourists are trickling back to marvel at the devastation that killed hundreds, wiped out the Philippines' main rice-producing region and forced the United States to abandon its largest overseas air base.

The emerging tourism business is helping the still-suffering villagers rise from the ashes. Several travel agencies, struggling against a slump, have turned to Pinatubo, targeting foreign and local tourists seeking adventure, unusual nature or a glimpse of history.

"This isn't really for the faint-hearted," says Mike Benneth of Dreamtreks, a small tour agency in Angeles City, near Pinatubo. "We cater to people with a taste for adventure."

Dreamtreks and a few small travel firms started escorting the three-hour climb up the 4,740-foot volcano in 1997 on the least treacherous of five routes discovered by Hilbero, an environmentalist and local tourism officer helping native Aetas displaced from their homes.

It opened a Web site with tour packages featuring photos of tourists trekking the volcano's slope and dipping into the crater's turquoise-blue waters. An overnight tour costs $70 per person, including food, bottled water, tents, sleeping bags, guides, transportation and a small fee at the starting point in Santa Juliana village.

From Santa Juliana, visitors are taken on a wild, bumpy, ride in old four-wheel-drive jeeps in a safarilike journey across the dusty expanse of Crow Valley to a campsite. The hike begins.

Crow Valley was a gunnery and bombing range for the U.S. Air Force and is still used by the Philippine Air Force for practice bombings. Tour organizers coordinate with the air force, check red warning flags in the field and scan the sky for signs of suspicious jet fighters.

From small numbers of mostly local tourists, visitors now number up to 1,000 a month, about a fourth of them foreigners, especially during the hot summer months from March to May, Hilbero says. Recent visitors included Manila-based executives of a multinational oil company on a team-building exercise.

"This place has a big potential but it hasn't been exposed much," says Danny Cerdena, a travel agency owner who joined Hilbero's climb to assess Pinatubo's tourism prospects. Cerdena says he now plans to include the volcano among his destinations.

Cerdena, based in Pampanga province, has partly depended on Pinatubo before, taking foreigners on a tour around devastated communities where churches and houses stand half-buried in volcanic mudflow.

More than 20 of Manila's largest travel companies are sending representatives to Pinatubo soon to study its potential, Cerdena says.

Pinatubo, about 55 miles north of Manila, exploded in June 1991 after a 500-year slumber, dumping billions of tons of volcanic debris on three provinces, erasing entire farm communities and altering the world's climate.

As a result, the U.S. government decided to abandon Clark Air Base at a time it was negotiating a new lease on the nearly 10,000-acre facility, then home to about 20,000 American soldiers, including their families. Their withdrawal, along with the pullout of American troops from nearby Subic Naval Base, ended nearly a century of U.S. military presence in the Philippines.

Pinatubo's eruptions were so massive that its top was simply blown away, reducing its height by 985 feet. Rainwater formed a crater lake.

During the rainy season, roughly from June to about October, climbing is forbidden as the volcanic debris on its slopes and in river channels become deadly avalanches.

Since Pinatubo is classed as one of the country's 22 active volcanoes, Benneth says Dreamtreks checks with the Philippine Institute of Volcanology and Seismology, which has a permanent monitoring station there, before every climb.

While scientists say it has a pattern of coming to life only every few centuries, they admit they aren't sure. Before 1991, the volcano last exploded 460 to 500 years ago.

Having scoured Pinatubo when it was a lush jungle, Hilbero says he was the first to conquer it two years after the 1991 eruption. He then led a few friends and outsiders on treks to the crater, gradually drawing back interest to the volcano as word spread about an out-of-this-world place sculpted by fire, water and wind.

Hilbero, also a local tourism officer, later helped tour agencies arrange visits to provide livelihood for Aeta natives, the aborigines who once thrived on hunting in the jungles of Pinatubo and surrounding mountains.

Hilbero and other officials are promoting a proposal before congress to declare Pinatubo an ancestral Aeta domain to protect them from the land grabbers and traders who have come in with the tourists.

There also are incidents of opportunistic villagers preying on outsiders. In Santa Juliana, considered Pinatubo's gateway, a newly painted sign outside a visitors' registry center reads: "Please beware of fake gold bars! There is no such thing."

The most popular trail to the volcano starts from Santa Juliana. Unlike the steeper, boulder-strewn other sides of Pinatubo, this trail rises so gently most of the way that the only indications of ascent are the brooks gushing toward you. Be careful; a couple are hot enough to boil eggs.

Over the last hour of the climb, the trail snakes into a steeper, narrower mountain pass scattered with stones and boulders but with more vegetation, a relief from the dreary gray of the path behind. When Hilbero and his entourage saw a bit of the sky-blue crater lake behind the rim, the panting throng managed a final dash to get a full view, then broke into yells.

When the euphoria subsided, some swam in the lake. Others dozed off their exhaustion during the two-hour stay in the crater.

The trek ends with an overnight stay in a campsite run by Aetas and lighted lit by a bonfire where we dine on fried chicken and steamed rice wrapped in banana leaves. We sleep on the ground in sleeping bags, our heads resting on our backpacks.