For the past week, before heading for the Phi Phi islands, I had traveled a path defined by Garland's book, from Bangkok to Surat Thani to Ko Samui and Ko Phangan and the other islands in the Ang Thong Archipelago. It was the tail of the season, a week before the monsoons would begin in the southern portion of Thailand; they had already begun up north.

What remained on the islands were mostly backpackers, young Europeans and a few Americans and Asians—people Garland certainly would have recognized, budget travelers who skittered around Asia looking for the unspoiled place even as they herded together in picturesque backpacker ghettos such as Ko Samui. Garland had in fact been one of them, as he had explained to me over the phone. "I'd been backpacking since I was 17, and I started out as a vicarious-thrill kind of backpacker who treated Southeast Asia as an adventure playground," he said. "I think later I started querying aspects of that, and that's what started the ball rolling with the book."

On a straight reading The Beach seems to cast backpackers into two types, divided by a shorthand ideology. The first is the sort Garland admits he once was, a thrill-seeker who looked on the native culture as an exotic treat and who charted his travels by the Lonely Planet guidebooks. The second type is the sort who feels outrage at the presence of other backpackers and who is ever seeking virgin spots yet unsullied by them. The character Richard falls into this category.

While the novel can read like a critique of the noisy, boorish, carefree vagabonds who swarm places like Khao San Road and Ko Samui, it's actually far more damning to pious travelers like Richard, who often muck up the pristine places they're so keen to discover. Unfortunately, this critical nuance can sail, untouched, over the dreadlocked heads of most of the young Western travelers hopping the jeweled islands of southern Thailand. Concurrent with the paperback publication of The Beach was its adoption as a sacred text for backpackers, and it was impossible to walk on a Thai beach without spotting a young foreigner sprawled on the sand with the novel, beach towel littered with postcards and cigarettes. More than one person told me they wished they could find a beach just like the one Richard finds. "I hear wildly different accounts from backpackers on what, exactly, the book means," Garland said to me. "And I accept that I misjudged and failed to represent some things in the way I wanted to represent them, and that I left them open to interpretation. But what was I going to do? I was 25 years old; I'd never written a book before. I got some things wrong."

As the tour boat made its way to the Phi Phi islands, it began to rain, a short squall which soon died away, the sky clearing to a milky white. At Phi Phi Don we moored beside several ferries carrying organized tour groups and a dozen speedboats that had brought backpackers and divers to the island. A few hundred yards up the beach ran a small line of shops and food shacks, and the tourists made for them. At the beach's opposite end grew a copse of curving palms, where the backpackers sprawled in the dark beneath. Thai girls in thin sarongs attended to them, massaging necks and legs while the scruffy young men reclined in satisfaction, some with drinks in their hands: a postcard of languid sensuality. I walked to an empty spot of sand between the shops and the shaded hollow, settled in, and dug a copy of The Beach out of my bag.

Beneath the entertainment of the novel's plot, Garland parries with the different ways in which to wander the world—with the notion that there are tourists and there are travelers and the breeds are distinct. "I had ambiguous feelings about the differences between tourists and travelers—the problem being that the more I traveled, the smaller the differences became," muses Richard in The Beach. "But the one difference I could still latch onto was that tourists went on holidays while travelers did something else. They traveled."

Richard is echoing a point made four decades ago by the historian Daniel Boorstin, who argued that in the middle of the last century—just at the time the word "tourist" first came into use—the character of foreign travel began to change. "It was the decline of the traveler and the rise of the tourist," Boorstin wrote in 1961. "The traveler...was working at something; the tourist was a pleasure-seeker. The traveler was active; he went strenuously in search of people, of adventure, of experience. The tourist is passive; he expects interesting things to happen to him."

It was peculiar, lazing in the sun within swimming distance of Phi Phi Lay and thinking about these twin islands passing from the hands of travelers and fully into the hands of tourists. In the early 1970s the few visitors who happened onto Phi Phi Don came for the unusually fine diving and snorkeling, or to climb the two islands' high cliffs and tally the exotic bird life. They were destinations with no amenities, and accommodation was a mesh hammock or a woven mat smoothed flat on the sand. But word gets out, as Garland's Richard laments, and greater numbers followed. Several bungalow hotels sprang up on Phi Phi Don, and a pizza joint or two, and then several bars serving hamburgers and tacos and warm Mr. Pibb. Even Lonely Planet grieved, and without irony, in the 1997 edition of its Thailand guide: "Bay packed with boats...new hotels building by the pier...endless rows of dreary, crowded bungalows," it laments. "Where's the nature? No one harvests nuts anymore and no one fishes. Why bother when you can ferry farangs around the coral reefs?"

Off on the horizon were even more foreign tourists, more farangs. The Thai government was counting on it. "This is the perfect commercial for the [marine] park, and for Thailand," Thai Forestry Director-General Plodprasop Suraswadi, whose agency issued the filming permit, said last March. "You couldn't buy better publicity for a tourist destination." The film's producer, Andrew Macdonald, joined in the boosterism: "Thailand will become famous as a country where paradise is possible."

Whether it does to the degree the bureaucrats hope is now mainly dependent on the filmmakers' skill, and following them, the critics. After all, the movie might stink. Early screenings suggested as much, or suggested trouble at least, as preview audiences found the film too dark and violent, all in all too un-Leo. Fox elected to shoot new scenes and re-edit the film, pushing the release date from a Titanic-like Christmas 1999 opening into the non-blockbuster precinct of mid-February 2000. And should the fixes not take hold and the movie flop, well then a pilgrimage is a hard sell, as Richard Bangs, founder of the tour company Mountain Travel­Sobek, discovered. "We saw no shortage of interest in Kenya after Out of Africa," Bangs told me. "So in 1992 we put together a trip called At Play in the Fields of the Lord, to northern Brazil. But the movie completely bombed, and there was no interest in the tour. It just died." Of course, the star of At Play in the Fields of the Lord was the actor Tom Berenger, and as any agent can also tell you, Tom Berenger is no Leonardo DiCaprio.

See, see, there's me on the Na Pali Coast on Kauai, where they filmed part of Jurassic Park; and that's Fripp Island in South Carolina, where Forrest Gump was made; and Squam Lake, New Hampshire, which is the real On Golden Pond; and that's the town in Finland where they shot Doctor Zhivago, except it looks so much like Russia that when tourists come to Saint Petersburg and want to know where the movie was, the Russians have to lie to them about it...