San Juan

The capital of Puerto Rico is a spirited modern metropolis with high-rise beach strips, a major commercial center and a justly famous historic colonial core. It dates from the early 16th century, making it the second-oldest city in the Americas (after granddaddy Cuzco, Peru). Today it's the engine of the island's economic and political life and the cultural beachhead for US influence in the Caribbean.

For an old timer, San Juan can seem pretty spry - nothing like strips of high-rise hotels and heaps of hard bodies littered about the beaches to make a town look young. Even Old San Juan seems strangely fresh and so well preserved given that it's getting on 500 years old. Many Caribbean adventurers never make it past San Juan: there's a lot to be said for being able to lay a towel down on an unmistakably white Caribbean beach while having the culture and quaintness of a historic city and the convenience of a modern metropolis just minutes away. But if day tripping appeals to you, the capital also makes a good base from which to explore the compact island.

El Yunque

The Taínos believed the god of happiness hung out on El Yunque, which is no doubt why hiking through the rainforest to this 1065m (3500ft) peak leaves travelers basking in the glow of well being, personal achievement, sore muscles and callused feet. The mountain is part of the Luquillo range and gives its name to the surrounding forest reserve, otherwise ostentatiously named the Caribbean National Forest. Tourist authorities are fond of promoting the reserve as the only tropical forest in the US national park system.

There are more than 400 tree and fern species in the 11,200 ha (28,000 acre) reserve, most of them growing like crazy in the hothouse conditions created when sopping clouds blown in by the Atlantic winds dump their load on the Luquillo range. There are 13 well-maintained hiking trails in the reserve, ranging from leisurely 15-minute prances along sealed paths to a trek to the peak of El Yunque. You might not see the Taíno spirit up top, but on a clear day you may bag an eyeful of the Virgin Islands.

If you stretch your legs in the rainforest, you'll hear the sing-song of the coquí frog (Puerto Rico's national emblem), see miniature orchids, get to play in waterfalls and maybe even glimpse the rare Puerto Rican parrot. El Yunque is less than an hour drive from San Juan, and there's road access to the reserve.

Luquillo Beach, not far from the El Yunque turnoff, is a popular seaside outing. The water is millpond flat, making it ideal for children, and though the slews of food and souvenir stalls mean this is no getaway, Luqillo's wide stretch of sand is still a picturesque picnic and dip spot.

Río Camuy Cave Park

This jagged karst region in the northeast of Puerto Rico is littered with sinkholes and surreal limestone formations so you don't have to have completed Geography 101 to guess that this is prime spelunking territory. Over 200 caves have been discovered in the region, some capable of swallowing skyscrapers, and the Camuy River is one of the largest subterranean rivers in the world.

Experienced cavers can get dirty and wet by climbing, scrambling, abseiling and swimming through the underground river system, but you have to know the difference between grappling and rappelling to contemplate entering this dangerous terrain. Mere mortals can get an antiseptic version of these thrills by riding a trolley-tram into a sinkhole and accessing Cueva Clara, which is graced with both stalagtites 'n' mites. From the safety of viewing platforms, you can glimpse the Camuy River as it flows past the 120m (400ft) deep Tres Pueblos Sinkhole.

Ponce

Nearly half a billion dollars have been spent preserving the colonial core of Puerto Rico's second city, and it's not only architecture buffs who declare the money well spent. The heart of Ponce dates from the late 17th century and has been declared a national treasure. It consists of plazas and churches and highly decorative colonial homes, some glorious fountains and what may well be the funkiest fire station in the world. One of the reasons Ponce is so easy on the eye is that an early city regulation required that street corners be chamfered (curved), making it easier for carriages to pass and to carry wooden houses from one site to another.

Ponce is a fraction inland on the central southern coast, and the locals are a breed apart from their brash northern cousins. They are justifiably proud of their civic heritage, the centerpiece of which is the stately Cathedral of our Lady of Guadeloupe that looms over the Plaza Las Delicias. The city's reputation as a center of cultural excellence comes in the modern form of the Ponce Museum of Art, the best in the Caribbean, and is enhanced by the Museum of the History of Ponce and the Puerto Rican Music Museum. If you're a sucker for a vista, the plexiglass Cruceta el Vigia just north of the center looks over Ponce to the sea. Eagle eyes might be able to pick out La Guancha, Ponce's boardwalk and beach area just south of the city. The swimming isn't great, but the social scene is buzzing.

The excellent Tibes Indian Ceremonial Center, a reconstructed Arawak village on an Amerindian archaeological site is about 15 minutes north of the town center. The 13 ha (32 acre) site was discovered in 1975 after hurricane rains uncovered pottery and only a small portion has so far been excavated. Access to the site is by guided tour only - it's a very interesting walk through a botanic garden, a reconstructed Arawak village, sporting grounds and the archaeological site where digging continues. The museum, though small, is well presented and informative.

San Germán

This picturesque town set in the southwestern foothills of the Cordillera Central looks like it was lifted lock stock and barrel from Mediterranean Spain. It's Puerto Rico's oldest settlement outside San Juan, and it wears its flaky plaster heritage with charm and aplomb. There's nothing more taxing to do here than take a genteel stroll through the town's two plazas, admire the courtly townhouses graced with gingerbread trim and poke your nose in the Church of Porta Coeli ('Gate of Heaven'). The latter was built by Dominican monks in 1606, and its august career includes a stint in the 19th century as the town jail.

San Germán is close to Phosphorescent Bay, where you can prove you're inhabiting the body electric, and Boquerón Beach, one of Puerto Rico's most gorgeous strands.

The best beaches in San Juan are at Isla Verde and Condado, both backed by a fortress wall of high rises. If you want to get out of the city (though not away from the crowds) try picturesque Luquillo, 30km (19mi) east of the capital, which is backed by nothing more intrusive than palm trees. The beaches on the southern coast are more sheltered and have calmer water for swimming than those on the northern Atlantic coast. In the south, there's a gem at Punta Guilarte near Arroyo. The west has a whole series of great beaches; the pick of the bunch is popular Boquerón. If you're exploring the islets off Puerto Rico, Flamenco Beach on Culebra regularly makes most people's regional top 10 list.

The best dives off Puerto Rico are a couple of kilometers offshore, since water visibility nearshore is often clouded by river runoff. Legendary Desecheo Island, west of Rincón, is perched on the edge of a 9km (5mi) deep submarine canyon and is regarded as one of the ultimate Caribbean diving destinations. Other top sites include La Parguera, off the southwestern coast; the islands of Culebra and Vieques, off Fajardo; Humacao, south of Fajardo; and Mona Island, a six-hour boat trip from Mayagüez. Sections of the northwestern coast near Isabela and Aguadilla offer shore diving, but water conditions can be rough and visibility poor.

You'll also need to hire a boat to reach the very best snorkeling sites. There a number of spots on the southwestern coast, notably around La Parguera. Other superb spots are the deserted islet of Palomenitos, off the coast of Fajardo, and Mona Island. For something completely different, it's definitely worth renting a boat or kayak to see the nightly displays of bioluminescence at Phosphorescent Bay near La Parguera and at Esperanza on the islet of Vieques.

The best surfing is along the northwestern stretch of coast between Rincón and Isabela between October and April. Serious windsurfers arrive in winter to take advantage of the swells on the northern Atlantic coast, particularly at Isla Verde. Rincón and Jobos near Isabela are also pretty hot, though beginners prefer the sheltered waters of San Juan's Condado Lagoon. If you're interested in sailing, Fajardo is the main yachting marina, and there are plenty of boats for hire. San Juan is the main deep-sea fishing charter port. There's world-class marlin, tuna and sailfish in the waters off the capital.

There are hiking opportunities galore in the island's interior, particularly in the rainforest of El Yunque, in the karst region of Río Camuy Cave Park and, for birdwatchers, in the coastal mangroves of the Guánica Reserve on the southern coast. If birds aren't big enough, there's humpback whale watching from Rincón between January and March.

Experienced cavers can explore the extensive underground sections of the Camuy River system with National Parks guides. Novices can take an expensive trolley-tram that accesses one cave via a sinkhole - be aware that weekends are so crowded that the experience is more rush hour transit than restful nature. Cockfighting may not be your idea of a relaxing Sunday afternoon, but if you have a strong stomach and want to see what excites the locals, fights take place in galleras in most country towns. The more sedate sport of kite flying is popular on the grassy, breezy slopes surrounding El Morro in San Juan, said to be the world's best kite site.

Every Puerto Rican town celebrates its saint's day, often with a mixture of pagan and Catholic iconography and Indian, African and Spanish traditions. There are solemn religious aspects and plenty of feasting, music, dancing and colorful costumed processions. One of the best is the Festival of St John the Baptist in San Juan in late June, which wonderfully fuses the religious and the secular. The highlight of the parade is a communal luck-enhancing midnight walk backwards into the sea. Worth a detour are Mayagúez's twinkling La Virgen de la Candelaria in early February and Loíza's jubilant St James Festival, which takes place late July and celebrates the town's multicultural heritage.

Old San Juan takes to the streets during the Saint Sebastian Street Festival in the third week in January. Ponce, where revelers dress up in horned masks for dancing and parades, is the best place to celebrate Carnival in February. In June San Juan's Casals Festival honors the famous cellist who came to call Puerto Rico home. It attracts classical musicians of international repute and is one of the Caribbean's major cultural events. Puerto Ricans get baseball fever when the season starts in November, reaching its climax in February.

Las Navidades between 15 December and 6 January is the peak period of socializing and religious observation, though many of the celebrations take place at family homes. Not so the riotous Festival of Innocents in Hatillo on 28 December, when masked and costumed participants chase kids through the streets in memory of Herod's bid to wipe out baby Jesus. Look out for parrandas, wandering bands of minstrels and revelers, around Christmas time.