MOOREA, French Polynesia - When Ghislaine Haamatearii was growing up on this South Pacific island, which author James Michener called ''too beautiful to describe,'' her mother would often invite passing tourists to join the family for an evening meal.

A Tahitian beach (Tahiti tourism)

''That doesn't happen anymore,'' admits Haamatearii, 30, who now ministers to strangers as owner of the local Inner Island Safari Tours. But unforced hospitality remains a hallmark of Moorea, its neighbor, Tahiti, and the 116 other islands and atolls that make up French Polynesia - even as residents brace for a tourism boom that officials hope will nearly double annual visitors to 350,000 by the year 2005.

High-profile admirers from Somerset Maugham to Marlon Brando have swooned over this French territory's romantic attributes. But these sparsely populated outposts have always disdained the mass-market approach that draws 4 million vacationers a year to Hawaii, about 2,700 miles northeast.

If an over-water bungalow in Bora Bora seems too mainstream for your Robinson Crusoe fantasies, take heart: Plenty of off-the-beaten-wake Pacific islands welcome intrepid tourists. A sampling: • Midway. Closed to the public for more than five decades after the pivotal World War II battle that remains its claim to fame, this former Navy base is now a National Wildlife Refuge. But the atoll, a two-hour flight north of Kauai via new jet service, isn't exactly a Lonely Planet kind of place. Ecotourists, scuba divers and fishing enthusiasts sleep in renovated barracks equipped with HBO, chow down at a beachfront French restaurant and can even rent cellular phones at $5 per day. Information: 888-574-9000 or www.midway-atoll.com . • Niue. Only 101 square miles, the ''Rock of Polynesia'' is praised by Moon Travel Handbooks as ''perhaps the most unspoiled island in the Pacific.'' Last year, only 2,041 visitors made the three-hour flight from Auckland, New Zealand, or the 11/2-hour flight from Tonga. Most come to dive the clear, reef-protected waters or explore a vast system of limestone caves. Above-ground excursions can include such traditional events as a teen-age boy's haircutting ceremony. To lure more vacationers (1998 goal: 120 Americans), Niue has established a U.S. tourist information bureau. Information: 425-688-8511 or www.visit.nu • Federated States of Micronesia. The Micronesian island of Guam has become a ''mini-Hawaii'' aimed at shopaholic Japanese tourists on package deals. But the more serene outposts of Yap, Kosrae, Phonapei and Chuuk (also known as Truk) offer some of the world's best diving and snorkeling sights, from huge schools of manta rays to the coral-encrusted remains of World War II destroyers. Continental Airlines serves the region from Honolulu, a 10-hour flight away. Information: 888-889-8100 or www.destmic.com . • Pitcairn. With no airport or harbor, the home to about 40 descendants of Bounty mutineer Fletcher Christian gives new meaning to ''isolated.'' Islanders are studying the feasibility of an airstrip that would open Pitcairn (about 3,300 miles east of New Zealand) to the outside world. For now, tourists are limited to sailors or passengers on a handful of expedition ships like Society Expeditions' World Discoverer, which calls at Pitcairn twice a year. • The Trobriands. This group of seldom-visited (fewer than 750 outsiders a year) atolls and islets lies about 100 miles east of New Guinea. Dubbed the ''Islands of Love'' by a Polish anthropologist who explored them in the early 1900s Information: 714-752-5440 or www.airniugini.com.pg

Just 40,000 Americans came to French Polynesia last year. Most of them stayed in small, expensive resorts on Tahiti or the nearby Society Islands of Moorea and Bora Bora, where roosters still outnumber cars and an elevated-over-water, thatched-roof bungalow will set you back more than $400 a night ($10 cheeseburgers and $7 mai tais not included).

Tahiti's capital, Papeete, may cope with the same crime and congestion problems as any other city of 185,000. Yet tourism there and elsewhere in the territory has been carefully orchestrated and tightly controlled: No high-rise condos, time shares or Planet Hollywoods.

But with the cutback in military spending that accompanied France's 1996 ban on nuclear testing in French Polynesia, the islands' self-imposed exclusivity is threatening to crumble.

A gaggle of U.S. companies such as Hawaii experts Outrigger Hotels, Pleasant Holidays and Runaway Tours have entered the Tahiti market in the past year. The influx has brought package deals as low as $759 a week per person, including hotel and airfare from the West Coast.

Radisson Seven Seas' swank 320-passenger Paul Gauguin launched one-week cruises from Papeete in January with Renaissance Cruises scheduled to base two 690-passenger ships there by the end of 2000.

And Bora Bora, hammered by a pair of hurricanes in December, hasn't seen so much construction since the U.S. Navy set up camp during World War II. Three resorts open there this summer, adding 215 rooms to the island's current 499 rooms in seven hotels.

French Polynesia's increased reliance on tourism worries residents like Bernhard Rickenbach, a Swiss native who moved to Papeete five years ago and married a Tahitian. He lectures on Polynesian culture aboard the Paul Gauguin, where afternoon tea is served by waitresses in stockings and black dresses and the artwork runs to 20th century modern.

Tahiti's success as a vacation destination ''depends on how tourists and operators approach it,'' Rickenbach warned his shipboard audience recently. ''We're already reaching maximum capacity at some of these places, and if (new visitors) start demanding air-conditioned buses and boutiques, we're going to have some problems.''

For now, at least, most of those concerns seem safely academic, particularly on French Polynesia's less-developed islands.

GETTING THERE: French Polynesia's capital, Papeete, is a 71/2-hour overnight flight from Los Angeles via Air France, AOM French Airlines, Air New Zealand or Corsair. Round-trip fares start at $600. LODGING: Costs range from about $50 a night for a room in a shared-bath pensione (bed-and-breakfast) to $750 for a one-bedroom fare (suite) at the venerable Hotel Bora Bora. Airfare/hotel packages are available from such tour operators as Islands in the Sun, Pleasant Holidays, Sunmakers or Runaway Tours; prices start at about $759 for a week in Tahiti and Moorea. SAILING: Another option is to explore the islands by sea. Radisson Seven Seas Cruises' Paul Gauguin sails weekly from Papeete to Huahine, Raiatea, Bora Bora and Moorea; the cruise line recently dropped Rangiroa as a port of call because of frequently choppy seas. Cruise-only fares start at $2,795 per person, plus discounted airfare of $150-$450 when booked through Radisson. Do-it-yourselfers can charter a sailboat in Raiatea; The Moorings, an outfit popular with North Americans, charges $420-$990 per day. DINING: Though tipping isn't expected, food costs can be steep, particularly in the major hotels. But quality is also high, thanks in part to the islands' French influence. Expect to pay from $5 for a crepe or croque monsieur (ham and cheese sandwich) at a roadside stand to $45 per person for a seafood dinner (without wine) at Bloody Mary's, a popular hangout on Bora Bora. Be sure to sample local favorite poisson cru, raw fish marinated in lime juice and coconut milk. WHEN TO GO: Summer is high season in French Polynesia, when prices are at their peak and the weather reliably benign; winter brings more rain and higher humidity. Each July, thousands of islanders gather in Papeete for the Haeva festival, a month-long party that encompasses music and tamure (dance) competitions, canoe races and other expressions of a resurgent Polynesian culture. INFORMATION: Tahiti Tourisme, 800-365-4949 or www.tahiti-tourisme.com

During a recent call at the ring-shaped coral island of Rangiroa - whose Aqua Velva-hued lagoon is so massive you can't see the other side - a handful of awestruck Paul Gaugin passengers joined residents at one of the atoll's biggest attractions: the mountainous seas that form in the lagoon's narrow passes as the tide roars in and out.

On Raiatea, where the soft air is laced with the scent of wild vanilla and tiare (Tahitian gardenia), hotel owner Marie-Claude Rajaud greets her guests in a swimsuit and pareo, the ubiquitous, brightly colored coverup that ranks as Tahiti's best-selling souvenir.

The island's 40-mile circular road can be nearly impassable on rainy days. But a visitor behind the wheel of a rental Fiat ($45 for four hours, plus gas at $4 a gallon) needn't worry: Chances are good that an obliging local will stop to offer advice on negotiating the daunting ruts.

Even Moorea, just a 20-minute ferry ride from Papeete across the Sea of the Moon, remains both serene and wild.

Beneath the surface, scuba divers cling to the rim of an ancient volcano, watching closely as their guide dangles the tattered remains of an enormous tuna. Within minutes, a platoon of 4-foot reef sharks moves in. Jaws snap. Eyes bulge. And Moorea delivers the thrill of a lifetime - or several.

Back on land, shark-toothed peaks jab the sky, fodder for tour guides' claim that they were Michener's inspiration for Bali Ha'i. (Alas, the real thing was about 2,400 miles west in the island nation of Vanuatu, where Michener penned Tales of the South Pacific.)

Moorea is a place where you can spend the better part of an afternoon sampling fresh fruit jams sold from a roadside stand. Where artist Stanley Haunani, the first Tahitian to become one of the Moorea gallery owners, is happy to explain both his vibrant watercolors and his longing for independence from France.

Native-born tour guide Haamatearii hopes that change comes slowly.

''More tourism is good for the people but bad for the islands,'' she says, gazing from Moorea's Belvedere lookout to the bay named for explorer James Cook.

''It's perfect the way it is.''