"The Galápagos are at a very difficult time in their history," says Johannah Barry, president of the Galápagos Conservancy, a longtime player in the effort to preserve the archipelago. "The Galápagos still maintain 95 percent of their original biodiversity, and in that, the Galápagos remain a success story. But when you have a wild place and a human population, the wild place generally loses. If we don't bring everybody to the table soon, the
Galápagos could be in real trouble."

Efforts have been made to protect the Galápagos - most notably the 1998 passage of the Special Law of the Galápagos, which recognized the islands' fragility (and the importance of tourist dollars) and established safeguards for the islands, from stemming ­immigration to extending the authority of the Park Service (the Galápagos became a national park in 1959) to establishing a 50,000-square-mile marine reserve, one of the largest in the world. Over the past five years, the Park Service has instituted strict quarantine rules, hoping to slow an influx of foreign plants and animals that Barry calls "extremely worrisome." But the obstacles are substantial, ranging from graft, powerful lobbyists, and political instability to the simple needs of man.

A fisherman I meet in Puerto Ayora, the Galápagos' largest town, spreads his hands.

"Why would people want to protect the animals when God gave us the animals to eat?"

And, so, there are two sides to the Galápagos.

"This is an amazing place," says Alex Arregui, one of our onboard naturalists. "But it is also sad to say that on the other side of this paradise, we have some serious problems."

I AM EXPLORING the Galápagos with Tauck World Discovery, a Connecticut-based operator whose Galápagos tours are intimately small and second to none. Tauck is environmentally active, contributing money to various Galápagos conservation causes, and by keeping their tours small they minimize the tours' impact. But it is their kind of first-rate offering - knowledgeable guides, opulent onboard meals, air-conditioned cabins with nightly chocolates on the pillow - that is introducing a special place to the world and altering it at the same time.

John Pumilio, our Tauck director and an insightful 33-year-old working toward a masters in environmental policy, puts it best.

"People are changed after they visit these islands," he says one night, as our vessel, the 237-foot MV Santa Cruz, throbs quietly toward yet another island. "Here they have a feeling of innocence. But tourism has to be controlled now. If you keep bringing more people here, that's a recipe for disaster. Fire can cook your food, or it can burn your house down."

Most visitors explore the Galápagos in the same way as our Tauck group, by ship - a handy prescription that keeps most lodging and dining at sea. Roughly 90 permitted tour vessels currently ply the islands. Most of these vessels are small by cruise-ship standards (our vessel carries 90 passengers), and some are as small as six-passenger sailboats, but I'm told that the large cruise-ship lines are knocking hard on the Galápagos' door. The ships ferry passengers ashore to islands via Zodiac, where tourists might hike, snorkel, or loll about pristine beaches. Not a single landing is unscripted; the Park Service schedules the comings and goings of the tour boats, and it certifies onboard naturalists, whose jobs are to both inform and police - keeping tourists on the trails and preventing uncomfortable scenarios such as, as one guide puts it, "having 500 pounds of angry blubber attached to your leg." By Park Service decree, we tourists are consigned to a narrow slice of the glorious whole; 97 percent of the Galápagos is national park, but the tourist strolls upon beaches and trails that represent only eight percent of the whole.

There are six naturalist guides aboard the MV Santa Cruz. My favorite guide is Alex. A native of Guayaquil, Ecuador, now living in the Galápagos, Alex has studied abroad in England, gaining advanced degrees in biology and ecotourism. He takes his educational responsibilities seriously - "It is important to understand the beauty and fragility of these islands," he tells me soberly - and as we hike about the islands in small groups, he fills our heads with reams of information, ranging from volcanism to the mating habits of marine iguanas. He knows his stuff, but he also possesses a wry sense of humor and a keen understanding of man's place in the Galápagos pageant.

Much ado has been made of the tameness of the Galápagos animals. When Darwin passed through the islands in the fall of 1835, he practiced hands-on science. Reaching into a hole, he yanked at the tail of a land iguana. Wrote Darwin later: "At this it was greatly astonished, and soon shuffled up to see what was the matter; and then stared me in the face, as much as to say, 'What made you pull my tail?' "

Today, the creatures of the Galápagos still practice a lovely snubbery that the most elitist country club couldn't match; sleeping, snorting, mating, eating, all the while ignoring man entirely. I've heard stories of Galápagos penguins pecking repeatedly at snorkelers' face masks, of birds landing on the arms of astonished hikers. On Santiago Island, I stood transfixed as a sea lion pup wobbled up to nibble my sandal.

It's bewitching, but there is sound reasoning behind it.

"Why do you see that the animals in the Galápagos are so tame?" Alex asks us one afternoon, as we admire a pile of marine iguanas resting inches from our feet.

"Because they are used to us?" offers one.

Alex smiles. The answer - because most of the animals have few, if any, natural predators - would wait for a beat.

"It has nothing to do with us," says Alex. "Man only just got here."

From a 130-year-old tortoise's standpoint, man's history in the Galápagos is merely a wink.

GIVEN MAN'S PROCLIVITY for greed and destruction, a wink can have a substantial impact.

The list of man's effects on the Galápagos is long; some are quite obvious, others nearly invisible. A handful of goats introduced to Isabela Island some 30 years ago exploded into a feral population of more than 100,000, and although many have been removed, they still require careful attention. In 2001, an oil tanker, the Jessica, ran aground at the entry to San Cristobal Island's Wreck Bay, spilling oil that reached nearby islands (fortunately, the damage was minimized by strong winds that blew most of the oil out to sea). Some fishermen, and, rumor has it, certain tour boats, dump trash and toilet discharge directly into the sea. Spores, insects, molds, and viruses arrive on shoe bottoms and in luggage. A ship anchors off an island for the night, and its blazing lights attract insects. When the ship pulls anchor the next morning, those insects travel on to the next island, adding new imbalance. And there are the towns, four of them, crammed into the three percent of land left to development. Coincidence or not, some tour boats eschew the towns entirely, furthering the illusion that the Galápagos are largely untouched.

Some say tourism is all that stands between the Galápagos and rampant degradation; even the most myopic Ecuadorian regime, they say, realizes that a Galápagos despoiled will no longer bring the tourists and their money. Others argue that tourism is responsible for its own substantial share of ills.

We visit Santa Cruz Island and Puerto Ayora on a bright and sunny day. Our schedule calls for a morning visit to the Charles Darwin Research Station and an afternoon in the highlands observing Galápagos tortoises.

I decide to skip the afternoon bus trip to the highlands because there are people I want to see - one in particular. I find Jack Nelson eating lunch alone at the Galápagos Hotel.

A soft-spoken man with the straightforward gaze of the self-sufficient, Jack came to the Galápagos in 1967. Few have his sense of perspective or his understanding of man's place in the Galápagos.

"The majority of the people who live here in the Galápagos don't understand or appreciate the value of conservation and sustainable development for their own future," says Jack. "A fisherman worries about today. Even an intelligent fisherman who sees the supply being wiped out thinks, 'If I don't get out there and get the last swordfish, someone else will.' To make matters worse, Ecuador is a politically unstable country. It's hard to adopt the long view when you've had five or six presidents in the last eight years."I walk with Jack to pick up his daughter at the school-bus stop. We stand in the hot equatorial sun. I ask about the future.

"I'm not pessimistic yet," Jack says quietly. "There's a tremendous amount of international attention on the Galápagos now, and that's a good thing. But there are plenty of problems to deal with, too."

Later, I pose the same questions to André Degell, another of our naturalist guides, and he simply shrugs.

"The problems of the Galápagos are the problems of the world," he says. "It's just that in this place, the problems are easier to see."

REGARDLESS OF THE SITUATION, the Galápagos still hypnotize. They are no longer untouched, but 600 miles of ocean and the resilience of nature remain something of a buffer to man's hand.

It's my last evening, and I'm strolling along the shore of North Seymour Island. Again, there are iguanas and sea lions scattered about, and kite-size frigate birds ­hovering languidly in the sky. This time, the setting sun, nearly below the horizon, turns the tide pools silver.

I watch several marine iguanas give mighty chuffs, expelling a stream of white liquid from their nostrils.

Alex materializes by my side.

"They are a-spitting," he observes. "They drink the seawater. When they get an excess of seawater, they're able to spit it out through the nostrils. Another amazing adaptation."

Alex regards the iguanas appreciatively.

"They live a very simple life, without wars, without material possessions," he says. "The Galápagos are in a very privileged place. It's good to be a long way from the mainland. We are away from all the chaos in the world."

An iguana rises on its haunches and swings heavily toward the ocean, making a sound like a sack dragged across sand.

Alex and I watch it slide into the water. Head raised, for a moment it snakes across the surface, swimming gracefully as evolution decreed, and then sinks into the ocean.

After a time, Alex speaks softly: "I think you have seen enough to understand."