GROWING UP on Rodgers and Hammerstein musicals has its drawbacks. For instance, when you set off on a vacation to the South Pacific.

After seeing "South Pacific" on the screen seven times, I can't think of a South Sea Island without conjuring up a vision of Bali H'ai, awash in a kaleidoscope of color filters and the stereophonic sweep of Richard Rodgers' music.

The problem is one of heightened expectations. Can any island live up to the paradisical promise of Bali H'ai? Seeking an answer--and an escape from a particularly frigid New York February--I set off for exotic-sounding Rarotonga, largest of the 15 Cook Islands, which lie in the center of Polynesia, flanked by Tahiti on the east and Samoa on the west.

First impressions upon sighting land are crucial, especially when you're expecting nothing short of picturesque perfection. Eleven hours out of L.A., I caught my first glimpse of Rarotonga. And it was nearly perfect. The plane's descent was the cue for dawn to light up the sky with yellow, pink and soft purple spots, just enough light to silhouette the jagged volcanic peaks lining the runway on one side and to throw back a fragile blue reflection from the lagoon almost lapping against the runway on the other side. A short minibus ride--all trips on Rarotonga are short since the island's total perimeter is only 20 miles--brought me to my hotel. After a short and futile effort to sleep, I changed into a bathing suit and headed for the beach.

Despite the fact that the island was solidly booked, this stretch of beach was all mine. Not another living soul was in sight. Not a single incongruous sight or jarring note interrupted my perfect vista of low clouds on the horizon, white Pacific spray crashing against the outer reef, the still turquoise of the inner lagoon and the white curve of beach strewn with shells and pebbles.

After ceremoniously dipping my toes in the South Pacific and hopscotching over the rocks to watch tiny fluorescent fish flashing in the low-tide pools, I stretched out on a towel and drifted into a delicious state of utter torpor.

If you did nothing more than lie on one of Rarotonga's pristine beaches for a week, it would be a vacation well spent. But Rarotonga has more drawing cards than its unspoiled tropical beauty and climate, perfect as they are.

For sports-minded visitors, Rarotonga offers tennis, riding, swimming, snorkeling, outrigger canoeing, spearfishing (day and night) and, a little more sedate, lawn bowling. On both Rarotonga and Aitutaki, an hour's flight away, there are nine-hole golf courses offering 18 holes with a par 64. And you can't argue with the greens fees. On Aitutaki, where one of the fairways skips over a landing strip, the fee is 50 cents.

But what makes Rarotonga different from any other island in the sun is that it has everything to perfection and in just the right amount. It delivers what the others only promise--an uncommercialized, uncomplicated, uncrowded and inexpensive away-from-it-all experience. And it has something that no other place in the world has--Rarotongans.

Whether you take a minibus tour around the island's narrow coastal plain, go on a reef-walking expedition or join a hike into the lush, mountainous interior, you'll meet Cook Islanders who'll treat you like a guest. Descendants of the Polynesians who populated the islands in migratory waves throughout the seventh and eighth centuries A.D., Cook Islanders are tall and attractive, outgoing and warm. Their own language is very similar to New Zealand Maori, but English (flavored with a distinctive New Zealand twang) is spoken by almost everyone.

Although the New Zealand government, with which the Cook Islands maintains a political and economic association, is pumping money into the island's tourist industry, it's still tourism on a very small scale. And it's tourism run by local people and aimed at the well-seasoned traveler rather than the "okay-so-entertain-me" tourist.

Exham Wichman is typical of the island's small tour operators. But there's nothing typical about taking one of his tours. He works on a very personal level, running horse-drawn buggy tours and charabanc outings while his wife, Maria, rents outrigger canoes to visitors--if there's no attendant around, you're asked to put your money in the Honesty Box.

With five other visitors, I climbed into Exham's charabanc, a custom-made open motor buggy with leather seats and no windows or roof to block your--or your camera's--view. It's a perfect touring vehicle.

Bumping along narrow dirt tracks in the township of Arorangi, where Exham has lived most of his 50 or so years, the charabanc lurched to a stop whenever Exham spotted something to point out or someone to introduce to us. Along the road, growing hot in the midday sun, Exham explained how virtually all the land on the island is still owned by families according to a tribal system. And since custom forbids selling land, it's impossible to assemble enough land to create large, efficient plantations--or large-scale resorts.

Exham pulled into an overgrown orange grove, where we all picked unpromising green oranges. With a machete-type knife, Exham peeled the green skins and lopped off the tops, advising us to suck the surprisingly sweet juice rather than eat the pulp.

Our next stop was Exham's house, a modern bungalow set among fruit trees, where his affable wife was waiting with a tray of cool mango wedges, lemons and tiny sweet bananas. This treat is part of Exham's personal marketing campaign to popularize the mango, known as pawpaw in the Cook Islands. By feeding pawpaw to every visitor, he confides, he hopes to convert enough fans to create an enthusiastic export demand.

Sitting around a picnic table shaded by grapefruit trees, the charabanc group ate pawpaw slices while Exham regaled us with local legends, missionary history and the story of the Bounty (of "Mutiny" fame), which sailed into Raratonga's harbor shortly after casting Captain Bligh adrift.

Maria reappeared with a steaming pot of tea and a plate of freshly baked scones accompanied by butter and preserves, and spread them out on an embroidered tablecloth. After devouring them wholeheartedly and adding our names to the family's guest book, we boarded the buggy for the return ride, feeling as though the Wichmans were old family friends.

After Exham's grass-roots tour, I headed downtown to see what Rarotonga's main town, Avarua, had to offer. Downtown is one street facing the harbor and lined with government bungalows, a post office, an outdoor fish market and trading company warehouses. These last barnlike buildings are a combined country general store, supermarket, duty-free shop and department store. It's an experience in itself just to wander among the counters and take in the variety of items for sale to an island-bound community.

Among the bolts of dry goods, I found a red and blue cotton print with the names of the Cook Islands incorporated into a busy but pretty pattern of flowers, fish and shells, for $2 a yard. For more traditional souvenirs, the best buys are at the Cook Islands Women's Federation, a house where handcrafted goods are sent by the island women on consignment. Here you can pick up a shell necklace or bracelet for as little as 50 cents, or an intricately woven grass skirt for as much as $50.

Currency is the New Zealand dollar, which is about on par with the U.S. dollar. A popular souvenir is the Cook Islands' own dollar coin featuring an engraving of the Islands' symbol, a well-endowed fertility god named Tangaroa.

Another favorite shopping stop for visitors is the Philatelic Shop at the post office. Cook Islands stamps are coveted by collectors around the world. In fact, stamps are the primary export of the islands.

As far as fashion goes, the best buy is a cotton pareu--a wraparound dress that the Cook Island women wear everywhere, even swimming. I paid $20 for a tropical red and white print and wore it out of the shop feeling much cooler than when I had gone in wearing shorts and T-shirt.

Nights in Rarotonga are best spent watching the sun set, reading a book on a veranda cooled by ocean breezes, finding a fisherman to take you out for moonlit fishing on the reef or just sitting on the beach stargazing. There's nightlife, too, but not of the big-city or resort variety. At the Banana Court you can soak up New Zealand beer (Leopard is the favorite) and local atmosphere and perhaps join in the dancing Wednesday, Friday and Saturday nights.

But the high spot of a visit to Rarotonga is to attend one of the Island Nights given at the Arorangi Beach Motel, the Trailways Motel or The Rarotongan, a luxury-class new hotel built by the New Zealand government.

The evening begins with a feast of native food cooked in an underground umu, an oven constructed of heated volcanic rocks and layers of plaited palm fronds. To the beat of drums and the trumpet of a conch shell, the oven is ceremoniously opened. Suckling pig and lamb emerge, tasting both smoky and slightly steamed.

There are also enormous oysters in unlimited quantity, salads of shellfish mixed with grated coconut and, to start, a tangy, rich Cook Island specialty, ikamata, chunks of raw fish marinated in lemon juice with raw onions, carrots and a dash of creamy coconut milk. The banquet ends with lusciously sweet slices of pineapple and ambrosial pawpaw wedges accented with a squeeze of lemon.

The bellow of a conch shell and the fevered beat of drums announces the beginning of the show. It's a spectacular performance, polished but never slick. Precision and grace make the Cook Islanders the best dancers and singers in the South Pacific, and their repertory is strictly authentic.

Another Cook Islands must is a visit to Aitutaki, the only other island that offers tourist accommodations. Cook Islands Airways operates a daily air service, flying twin-engined Britten-Norman islanders on the hourlong trip. You have to weigh in before you can board the eight-passenger plane. With luck you may get the seat beside the pilot, as I did, and enjoy playing copilot as well as having the bird's-eye view.

Aitutaki appears on the sparkling blue sea looking like an emerald on a turquoise Faberge' egg. It's encased by one of the largest and most beautiful lagoons in the South Pacific. The water is so still and clear that as the plane approaches the World War II--vintage coral landing strip, you can see every detail of the coral formations on the lagoon bottom.

The island is lush and strictly agricultural, with small villages containing a total population of 2,500 dotted around the coast, a post office, a small hospital and a fascinatingly incongruous 19th-century wooden church with a frescoed ceiling.

The Rapae Motel is the only hotel on the island and it's charming--12 veranda-fronted cottages and one family unit. Just yards from the beach there's a rattan bar, redolent of Somerset Maugham, and an open-air dining room with a thatched roof rewoven each year by the nearby villagers.

Mouth-watering fresh fish is served at tables decorated with conch shells brimming with exquisitely arranged orchids, hibiscus and frangipani, all of which grow wild throughout the islands.

Aitutaki's pace is barely perceptible. There's time and space to lose yourself completely or to observe the island way of life and meet some of the residents.

For those who like to rough it and have plenty of time to spare, Aitutaki can also be reached by romantic, though unscheduled, interisland trading ship. Only 140 miles from Rarotonga, it's also accessible from your own boat.

Raratonga has long been a favorite stopover for yachtsmen cruising the South Pacific, as it's in the middle of the triangle formed by Samoa, Fiji and Tahiti. Using Rarotonga as a starting point, sailors can head north to Aitutaki, stopping in at four other lush, green islands along the way--Atiu, Mitaro, Mauke and Mangaia.

The rest of the Cook Islands are sea-level coral atolls, sparsely populated, if at all, but just the stuff sailors' dreams are made of. One New Zealander named Tom Neale did in fact realize his dream by living entirely alone on one of the uninhabited islands for several years.

Not until I glanced out the airplane window at the concrete towers of Honolulu emerging from under a low-flying bank of clouds did I begin to come out of the trances that the Cook Islands induces. Amid the bustle and noise of excited tourist crowds in the Honolulu airport, I wondered if the Cook Islands would be able to withstand commercialism.

I thought back to the serene islands where, by law, no building is allowed to be taller than a palm tree. And to the unique welcome sign at the Rarotonga airport: "Tipping is not customary in the Cook Islands. Thank You." For a while, at least, I think the Cook Islands are safe.