In Virgin Gorda, the best sightseeing is underwater

The great charm of Virgin Gorda is that it's so small you know you're on an island. You can always see water, sometimes on all sides. The trade winds blow gently but steadily over you all day and even while you sleep, since there are no windows here, only screens. You get the illusion of motion, as if the whole nine-mile-long island were chugging down to South America.

The island has a very satisfying feeling of solitude, whether you're alone, with your new spouse (this is a popular honeymoon spot) or with friends. On a map, it appears modestly as a speck in the British Virgin Islands, a spray of dots that seem to have been flung off the east end of Puerto Rico. In person, it's a tiny world unto itself, and a visitor endows everything on it with special, maybe even magical qualities.

Roosters crow in the morning all over the world, but the one outside one's door seems unique. Maybe because he's standing with a land crab and a cat, and they're all the same height. The mountain on Virgin Gorda isn't awesome, but it's the mountain, and since the island is only nine miles long, it manages to loom.

The old copper mine, dug by the Spanish 300 years ago, is just a pile of stones, but its lone chimney is a haunting sight at the end of a bow of green, bushy land and turquoise water. These, and ''The Baths,'' a pile of house-size stones tumbled into the ocean at one end of the island, complete with caves and protected pools, become the wonders of your world. It's surprisingly easy to scale down.

It's too hot to walk very far, but that doesn't really matter. The best sightseeing is underwater. Brilliant fish dart around the seascape or seem to hang in the water, poised in groups like mobiles. In a mask and snorkel (which you can get at your hotel or rent from Dive BVI) you begin to move like one of them, slowly and quietly, and an hour can go by while you investigate two or three fascinating rocks or a batch of irresistible coral.

If you want to go deeper, there are two diving services on Virgin Gorda - Kilbride's Underwater Tours at the Bitter End Yacht Club, and Dive BVI at the marina. Joe Giacinto, owner of Dive BVI, says Virgin Gorda is one of the supreme places for scuba diving in the Caribbean because the water is clear and warm, and it doesn't take long to get to good dive sites. The visibility underwater is 100 feet, and there are wrecked ships all over to explore. Giacinto will take a group of divers out to selected spots, bring them back for lunch, or bring a picnic if they are to dive all day. He also offers an introduction to nondivers, which, he reasons, is a better way to find out if you like scuba diving than by taking a plunge at your local YMCA.

Whether you dive, windsurf, or just lie down a lot, Virgin Gordians are what make this scruffy mountaintop so pleasant. Walking down the road next to a woman carrying a baby, I asked if she would like me to carry him for a while. She handed him over, even though she really didn't need any help and was only about 20 yards from her destination.

You feel indulged in simple ways. Farther down the road, a little girl came up to me, said ''Hi!'' brightly, and put her hand in my hand.

Basically, everyone is here to help you, because tourism is the industry on Virgin Gorda. You get the feeling they're happy with the arrangement. Prices are high, but no one tries to make you buy anything. Tourism was inaugurated in grand style when Laurance Rockefeller bought 365 acres and opened Little Dix Bay in 1964. Little Dix Bay is a well-manicured Rockresort cuddled around a spanking white beach. Perhaps because the resort didn't take over the whole island, and people have good jobs there, Virgin Gordians seem self-possessed. They probably still feel as much at home here as they ever did.

This could be a challenge, considering the strange behavior of some of the visitors. I was on an errand one day at high noon, striding down the road while all the sensible people were inside. As I passed a shady veranda, a little voice piped curiously, ''Sun hot?''

Practical information:

There are other hotels besides Little Dix Bay. Fischer's Cove, the one I stayed in, has small, triangular cottages with kitchens and bathrooms, as well as regular hotel rooms. The hotel has its own beach. Cottages are $90 a day or $ 395 a week double, and $180/$525 for a two-bedroom house, European plan. Rooms are $115 a day double, $85 single, modified American plan. For reservations, call (212) 371-6755.

Little Dix Bay offers horseback riding, sailing, water taxi service to any beach, and tennis. It's generally a little manicured world within the little world of Virgin Gorda. Rooms are in low bungalows among trees by the bay. Daily rates are $305 single, $350 double, and $700 for a cottage. This includes all meals. To call Little Dix Bay, it's 800-223-7637; in New York City it's 586-4459 .