Are you tired of going to places so dominated by the tourist business that you see nobody but other tourists and sullen hotel employees?

Some say that many Caribbean islands have been spoiled by the vacation traffic, that Cozumel off the Yucatan coast hasn't been the same since it took on the big hotels and the jet strip, and that the new resort Cancun a few miles away never was anything but a tourist haven.

If you object to vacationing in a social vacuum, sealed off from the daily life that goes on around you, you could do worse than Isla Mujeres.

It's a tiny streak of land, 5-miles-by-one-half, a mile or two north of Cancun and just a 45-minute ferry ride from Puerto Juarez, the tip of the Yucatan Peninsula. Though there are two or three fairly fancy hotels on the island, it is still basically a fishing village. And there are people who want to keep it that way.

One of these is Pepe Ponce, who runs a hostel for the adventurous - mostly young, but a few in their 70s - called Poc-Na, with bunks and hammocks at prices ranging from $2, and private cottages.

"Isla Mujeres could be just another tourist island," he said, "or it could be something special. We hope to get some balance here: conventional hotels, the family hotels and pensions, the campgrounds. We may encourage some light industry."

Twenty years ago the island had nothing, he added, and there is still some confusion among the townspeople over the ever-increasing invasions of gringos. One by one, the sandy side-streets in the village (population - 1,500) are being payed. Motorbike rentals, the big tourist business, ar proliferating. Fishing boats make daily trips to El Garrafon beach, where the impossibly clear limegreen water shows you thousands of phantasmagoric fish and underwater plants.

You can pet the giant turtles in the pens and dine on broiled barracuda, a delicacy even in his fish-conscious place.

A little Spanish helps, a few words from a phrase book. Unfortunately, many visitors don't make the effort and content themselves with sing language. They don't even learn the coins.It is embarrassing to see a fellow American hold out a handfut of change for the store clerk to select what is owed him.

One also senses now and then a local wariness of the bearded, the youthful, the barefooted, since hundreds of students descened on the island during vacations, sometimes taking advantage of easygoing natives.

Ponce hopes to channel the energy of the young visitors. On his five-acre oceanside property he plans a large hostel "to take care of their basic needs at the lowest possible price" and a study center, specializing in languages, Mayan culture and music.

It should contrast nicely with the huge international hotel, the Zazil-Ha, now being rebuilt. The island campground is also pleasant, located in a palm forest at the edge of the lovely white-sand north beach. There are mosquitoes at night. Campers should bring netting.

But the drawbacks are few. You fish, or swim, or snorkel with equipment from the local dive shop. You bake on the beaches (with caution; by March the sun can be fierce), splash about in the beautiful water, take a siesta in a hammock.

In the evenings you drift about the village, top at a stall for a cocktail of pineapple, mango and melon, roam the square (where the movie house is showing an old Tarzan picture and the town prostitute is parading her latest customer) and finally pick a restaurant for a superb dinner of conch, lobster or vension, which is still very big on the Yucatan.

If you're lucky you might rent a cottage on the oceanside beach, with a tile floor and big wodden shutters through which the soft trade winds blow day and night (and through which also the neighboring family's pet donkey is apty to stick his snout), a peaceful spot where you can watch the sun coming up scarlet over the horizon or you simply sit on the sand and stare at the incredible blue sea and wish you could stay forever.

To get there: Buses run daily to and from Merida, 200 miles away. Several airlines have service to Cancun and Cozumel, from which you can take bus and ferry to Mujeres. There are flights to these islands from Merida. At Puerto Juarez, where you take the ferry to Mujeres (50 cents), there is a protected parking lot where you can leave your car for 75 cents a day. For those with campers, or those few who cannot be without a car even on a 5-mile island, there is a car ferry, too ($2.50)

P.S.: If you haven't visited Mexico in 15 years or so, you will be delighted to learn that the food and water situation is vastly improved, at least on the Yucatan. With common sense, you can eat anything you would at home. There are those who insist you can drink the tapwater, though the facts is that most hotels supply pitchers of water in the rooms, which does not inspire great confidence in the taps.