RINCON, Puerto Rico -- So many beautiful beaches around the world are ringed by high-rise condos, trinket shops and traffic, with the same fast-food and hotel chains as all the other beaches.

But Puerto Rico's west coast is different. It has sand, sun and sea, but so far, it's avoided the overdevelopment that can turn beach towns into generic megaresorts. Instead, on a recent family trip, we found friendly cafes, funky surf shops, small towns and tranquil beaches on the byways.

Rincon, on Puerto Rico's northwest coast, has the laidback vibe of a surfer town. But the chirping of the coquis -- tiny tree frogs that sing dusk to dawn -- leaves no doubt that you are in Puerto Rico.

Peter Aviles, who grew up in Rincon and is the editor of the Rincon-PR.com Web site, says surfers put Rincon on the map when teams from around the world showed up to compete in the 1968 World Surfing Championship. Rincon is located on a peninsula, with waves from the Atlantic on the north side of the point and calmer Caribbean seas on the southern side.

Aviles said there only was one hotel in town when the surfers arrived, Villa Cofresi, and when that filled up, locals started renting out rooms.

"That was the beginning of the lodging industry here," he said.

Today Rincon has about 1,000 rooms among various hotels, B&Bs and rentals, but it retains a small-town feel with a year-round population of about 15,000 and zoning that prohibits buildings over four stories on the beach, Aviles said.

Between November and February, surfers come for the big waves at beaches like Tres Palmas and Domes Beach, and North Americans come to escape the cold. In March and April, migrating humpbacks make whale-watching a major attraction. From May through August, it's a summer beach town.

"We were just there watching the whales from our back porch," said Clifton Elgarten, who lives in Washington D.C. and owns a home in Rincon. He flies down with his family a half-dozen times a year. "I like the town because it feels like a town, not a resort."

He added that "there's always a threat of development," and new condos have recently sprung up, "but so far the town hasn't lost its character, and we are grateful."

Villa Cofresihas just 69 rooms, but is one of Rincon's three largest hotels -- further evidence of the town's small scale. Cofresi is by no means fancy, but it offers a beautiful beachfront location and comfortable rooms. It's named for Roberto Cofresi, a 19th century pirate. At night, the hotel bar and restaurant pulse with music, the click-clack of balls on the pool tables and a fun party vibe, but at the breakfast buffet and on the beach, you see mostly couples and families -- from the U.S. and from Puerto Rico -- many of whom return each year.

Winding roads around Rincon lead to various public beaches. One day my sister and the kids went parasailing. Another day, we rented snorkeling gear for $10 and went snorkeling at Steps Beach. At a friendly little surf shop just up the road from Maria's Beach, we arranged for surfing lessons. Nearby, a man sold coconuts for $1, which he hacked open with a machete and stuck a straw in.

We also drove down the west coast from Rincon to Cabo Rojo in search of Bahia Sucia. We thought we might be lost when the paved road gave way to a bumpy dirt road. Then suddenly we beheld the beach, a stunning crescent with turquoise water and white sand as fine as sugar. The name Bahia Sucia translates as "dirty bay," and I heard various explanations for it -- a long-ago oil spill, the dirt road, seaweed -- but the place appeared pristine.

Egrets fish in a marsh behind the beach and Los Morrillos, a 19th century lighthouse, towers in the distance atop a cliff. We swam, relaxed in the shade of a few small trees, and the boys and my husband hiked along the cliffs that circle the beach.

The beach is undeveloped, which is part of its charm, but we hadn't brought drinks, so after a while, we needed refreshments. A hotel we'd passed on the way, Bahia Salinas, looked unremarkable from the outside, but inside it was a serene oasis with an infinity pool, cabanas draped in gauzy white curtains and a parrot that says "Ola!" We ordered drinks and enjoyed the view, which reminded me of the Everglades.

From there we headed to La Parguera, a harbor town on Puerto Rico's southwestern coast with a phosphorescent bay, where you can swim at night amid microscopic organisms that glitter when the water is disturbed. But we found no signs or storefronts advertising boat rides. We wondered if we were in the right place when a man came up to our car and asked if we were looking for the biobay. Through him, we bought tickets, $6 each, for the after-dark excursion.

We got lost driving back to Rincon, but just like every other time, we found our way after a few wrong turns and directions from the locals. An early flight the next morning precluded a last swim in the sea, but we did have one final "you know you're in Puerto Rico" experience: The coquis serenaded us in the predawn darkness.