White sandy beaches put Puerto Rico and its offshore islands on tourist maps in the first place. Many other Caribbean destinations have only jagged coral outcroppings or black volcanic-sand beaches that get very hot in the noonday sun.

Condado Beach: Although not the best in the Caribbean, San Juan's Condado Beach is the most famous--which helps explain the wintertime crowds. It is also the most popular in Puerto Rico because of its proximity to San Juan. Once the stamping ground of the rich, including the Vanderbilts and the Rockefellers, this 2-mile band of white sand winds between a blue lagoon and some of the Caribbean's finest resort hotels. High society began coming here after Cornelius Vanderbilt constructed the Vanderbilt Condado Beach Hotel in 1919. In the 1970s, the beach's popularity mushroomed as fast-food restaurants, water-sports concessions, restaurants, and condos emerged from a massive construction boom.

Luquillo Beach: About 30 miles east of San Juan, Luquillo Beach sits in a crescent-shaped bay edged by a vast coconut grove, which makes it not only the best beach in Puerto Rico, but one of the finest in the entire Caribbean. Coral reefs protect the crystal-clear lagoon from Atlantic waters that can batter the coast. Much photographed because of its white sands, it also has tent sites and other facilities, including picnic areas with changing rooms, lockers, and showers. Regrettably, Luquillo Beach isn't as well maintained as it used to be, although it remains the favorite of beach buffs from San Juan. In winter, it's also inhabited by "snowbirds" (condo owners from up north who live nearby).

Playa Dorado: West of San Juan, Playa Dorado consists of six white-sand beaches along the northern coast, reached by a series of winding roads. This whole area is dominated by the Hyatt resorts, Cerromar and Dorado. Because the hotels offer numerous children's programs, the Dorado beaches have become a family favorite. Originally, the beaches opened onto a grapefruit and coconut plantation owned by Clara Livingston, Puerto Rico's first female pilot. As fruit prices declined in the 1950s, she sold off her 1,600 acres to Laurence Rockefeller, who began hotel construction.

Playa de Ponce: The beaches on the southeast coast west of Ponce, the "second city" of Puerto Rico, are far less crowded than those of the Condado, Luquillo, and Dorado. This long strip of white sand opens onto the tranquil waters of the Caribbean. Several very good seafood restaurants are in the vicinity.

Boquerón Beach: South of Mayagüez, Boquerón Beach is the Cape Cod of Puerto Rico. This beach town stands at the heart of a 3-mile bay, with palm-fringed white sand curving away on both sides. Fishermen, sailors, scuba divers, and windsurfers, as well as beach devotees, are attracted to this beach, where fresh oysters shucked on the spot and doused with Tabasco are sold from shacks. Here the ice cream is made with sweet corn and dusted with paprika (it sounds awful, but tastes good).

The Secret Beaches: The main island is filled with isolated sandy coves that only the locals seem to know about. The best, all guaranteed to delight the escapist in you, stretch between Cabo Rojo (the southwesterly tip of Puerto Rico) all the way east to Ponce. Beginning in the west, directly east of Cabo Rojo, you'll discover Bahia Sucia Beach, Rosada Beach, Santa Beach, Manglillos Beach (with a recreation area), Caña Gorda Beach, Tamarindo Beach, and Ballena Beach. Access to many of these is limited because of poor roads, but the effort is worth it. Bring along the supplies you'll need.

Doral Palmas del Mar Resort (Humacao; tel. 800/725-6273 in the U.S. or 787/852-6000): The huge Palmas del Mar resort near Humacao on the eastern coast of Puerto Rico has been called "the new American Riviera." Although the architectural dream of this 2,750-acre playground resort built on a former coconut plantation hasn't been realized yet, the site is fully functional and sports 3 miles of white-sand beaches. Unlike some of the rough-water beaches near Rincón in the west, the sea here is tranquil and calm year-round. There's also a water-sports center and marina.

With the continental shelf surrounding it on three sides, Puerto Rico has an abundance of coral reefs, caves, seawalls, and trenches for divers of all experience levels to explore.

Metropolitan San Juan: This easy beach dive off the Condado district in San Juan is not as spectacular as other dives mentioned here, but certainly more convenient. Lava reefs sculptured with caverns, tunnels, and overhangs provide hiding areas for schools of snapper, grunts, and copper sweepers. In the active breeding grounds of the inner and outer reefs, divers of all levels can mingle with an impressive array of small tropical fish--French angels, jacks, bluehead wrasse, butterfly fish, and sergeant majors, among them--along with sea horses, arrow crabs, coral shrimp, octopuses, batfish, and flying gunards. Visibility is about 10 to 20 feet. The Condado reef is also ideal for resort courses, certification courses, and night dives.

Mona Island: Mona Island, 40 miles west of the city of Mayagüez in western Puerto Rico, is considered to be the Caribbean version of the Galápagos Islands. Renowned for its pirate tales, cave-pocked cliffs, 3-foot-long iguanas, and other natural wonders, its waters are among the cleanest in Puerto Rico, with horizontal visibility at times exceeding 200 feet. More than 270 species of fish have been found in Mona waters, including more than 60 reef-dwelling species. Larger marine animals, such as sea turtles, whales, dolphins, and marlins, visit the region during migrations. Various types of coral reefs, underwater caverns, drop-offs, and deep vertical walls ring the island. The most accessible reef dives are along the southern and western shores. Getting there is a pain, however. You must brave a 5-hour boat ride across the often rough Mona Passage.

Southern Puerto Rico: The continental shelf drops off precipitously several miles off the southern coast, producing a dramatic wall 20 miles long and teeming with marine life. Compared favorably to the Cayman Islands' wall, the Puerto Rican version has become the Caribbean's newest world-class dive destination. Paralleling the coast from the seaside village of La Parguera to the city of Ponce, the wall descends in slopes and sheer drops from 60 to 120 feet before disappearing into 1,500 feet of sea. Scored with valleys and deep trenches, it is cloaked in immense gardens of staghorn and elkhorn coral, deep-water gorgonians, and other exquisite coral formations. Visibility can exceed 100 feet. There are more than 50 dive sites around Parguera alone.

Fajardo: This coastal town in eastern Puerto Rico offers divers the opportunity to explore reefs, caverns, miniwalls, and channels near a string of palm-tufted islets. The reefs are decked in an array of corals ranging from delicate gorgonians to immense coral heads. Visibility usually exceeds 50 feet. You can hand-feed many of the reef fish that inhabit the corals. Sand channels and a unique double-barrier reef surround Palomino Island, where bandtailed puffers and parrot-fish harems are frequently sighted. Cayo Diablo farther to the east provides a treasure box of corals and marine animals, from green moray eels and barracudas to octopuses and occasional manatees.

Bring your boots. Puerto Rico's mountainous interior offers ample opportunity for hiking and climbing, with many trails presenting spectacular panoramas at the least-expected moments.

El Yunque (tel. 787/888-5670 for information): Containing the only rain forest on U.S. soil, this Caribbean National Forest east of San Juan offers a number of walking and hiking trails. The rugged El Toro trail passes through four different forest systems en route to the 3,523-foot Pico El Toro, the highest peak in the forest. The El Yunque trail leads to three of the recreation area's most panoramic lookouts, and the Big Tree Trail is an easy walk to La Mina Falls. Just off the main road is La Coca Falls, a sheet of water cascading down mossy cliffs.

Guánica State Forest (tel. 787/721-5495 for information): At the opposite extreme of El Yunque's lush and wet rain forest, Guánica State Forest's climate is dry and arid, the Arizona-like landscape riddled with cacti. The area, cut off from the Cordillera Central mountain range, gets little rainfall. Yet it's home to some 50% of all the island's terrestrial bird species, including the rare Puerto Rican nightjar, once thought to be extinct. The forest has 36 miles of trails through four forest types. We prefer the mile-long Cueva Trail, where hikers look for the endangered bufo lemur toad, another species thought to be extinct but still jumping in this area. Within the forest, El Portal Tropical Forest Center offers 10,000 square feet of exhibition space and provides information.

The Historic District of Old San Juan: There's nothing like it in the Caribbean. Partially enclosed by old walls dating from the 17th century, Old San Juan was designated a U.S. National Historic Zone in 1950. Some 400 beautifully restored buildings fill this district, which is chockablock with tree-shaded squares, monuments, and open-air cafes, as well as shops, restaurants, and bars. :If you're interested in history, there is no better stroll in the West Indies.

Castillo San Felipe del Morro: In Old San Juan and nicknamed El Morro, this fort was originally built in 1540. It guards the bay from a rocky promontory on the northwestern tip of the old city. Rich in history and legend, the site covers enough territory to accommodate a nine-hole golf course.

The Historic District of Ponce: Second only to Old San Juan in terms of historic significance, the central district of Ponce is a blend of Ponce Créole and art deco building styles, dating mainly from the 1890s to the 1930s. One street, Calle Isabel, offers an array of Ponceño architectural styles, which often incorporate neoclassic details. The city underwent a massive restoration preceding the celebration of its 300th anniversary in 1996.

Museo de Arte de Ponce: Also in Ponce, this museum has the finest collection of European and Latin American art in the Caribbean. The building itself was designed by Edward Durell Stone, who also designed the Museum of Modern Art in New York. Contemporary work by Puerto Ricans is displayed, as well as an array of old masters, including Renaissance and baroque works from Italy.

Tropical Agriculture Research Station (Mayagüez): These tropical gardens contain one of the largest collections of tropical species intended for practical use. These include cacao, fruit trees, spices, timbers, and ornamentals. Adjacent to the Mayagüez campus of the University of Puerto Rico, the site attracts botanists from around the world.

The City of San Germán: In the southwestern corner of Puerto Rico, and founded in 1512, this small town is Puerto Rico's second-oldest city. Thanks to a breadth of architectural styles, San Germán is also the second Puerto Rican city (after San Juan) to be included in the National Register of Historic Places. Buildings, monuments, and plazas fill a 36-acre historic zone. Today's residents descend from the smugglers, poets, priests, and politicians who once lived here in "the city of hills," so-called because of the mountainous location.