68 to 77 miles (109-124km) W of San Juan

Getting There

Arecibo Observatory lies a 1 1/4-hour drive west of San Juan, outside the town of Arecibo. From San Juan head west along four-lane Rte. 22 until you reach the town of Arecibo. At Arecibo, head south on Rte. 10; the 20-mile (32km) drive south on this four-lane highway is almost as interesting as the observatory itself. From Rte. 10, take exit 75-B and follow the signposts along a roller-coaster journey on narrow two-lane roads. First you will go right on Rte. 652 and take a left on Rte. 651. Proceed straight through the intersection of Rte. 651 and Rte. 635, and then turn left at the cemetery onto Rte. 625, which will lead you to the entrance of the observatory.

On the same day you visit the Arecibo Observatory, you can also visit the Río Camuy Cave Park. The caves also lie south of the town of Arecibo. Follow Rte. 129 southwest from Arecibo to the entrance of the caves, which are at Km 18.9 along the route, north of the town of Lares. Like the observatory, the caves lie approximately 1 1/2 hours west of San Juan.

Exploring the Area

To get to the Observatorio de Arecibo, take Expwy. 22 heading east. Take Rte. 129 south toward Utuado for about 2.5 miles. Go left at the Texaco Station on to Rte. 635 for about 1.25 miles, then take a right at the crossroads to stay on Rte. 635, and follow the road for another 3.5 miles, when you’ll have to turn right to remain on the road. Continue for another half mile, then take a left at the cemetery to Rte. 625. Follow road for about 3 miles until the entrance of the Observatory.

Dubbed “an ear to heaven,” Observatorio de Arecibo (tel. 787/878-2612; www.naic.edu) contains the world’s largest and most sensitive radar/radio-telescope. The telescope features a 20-acre (8-hectare) dish, or radio mirror, set in an ancient sinkhole. It’s 1,000 feet (305m) in diameter and 167 feet (51m) deep, and it allows scientists to monitor natural radio emissions from distant galaxies, pulsars, and quasars, and to examine the ionosphere, the planets, and the moon using powerful radar signals. Used by scientists as part of the Search for Extraterrestrial Intelligence (SETI), this is the same site featured in the movie “Contact” with Jodie Foster. This research effort speculates that advanced civilizations elsewhere in the universe might also communicate via radio waves. The 10-year, $100-million search for life in space was launched on October 12, 1992, the 500-year anniversary of Columbus’s arrival on the shores of the New World.

Unusually lush vegetation flourishes under the giant dish, including ferns, wild orchids, and begonias. Assorted creatures, such as mongooses, lizards, and dragonflies, have also taken refuge there. Suspended in an outlandish fashion above the dish is a 600-ton (544,311kg) platform that resembles a space station. This is not a site where you’ll be launched into a “Star Wars” journey through the universe. You are allowed to walk around the platform, taking in views of this gigantic dish. At the Angel Ramos Foundation Visitor Center, you are treated to interactive exhibitions on the various planetary systems and introduced to the mystery of meteors and educated about intriguing weather phenomena.

Visiting hours are Wednesday through Sunday and most holidays from 9am to 4pm, but during the Christmas season (Dec 15–Jan 15) and summer (June–July) visitors are welcome every day. The observatory is closed to visitors on eight holidays: Good Friday, Easter, Mother's Day, Father's Day, Thanksgiving, Christmas, New Year’s, and Three Kings Day (Jan 6). There’s a souvenir shop on the grounds. Plan to spend about 1 1/2 hours at the observatory (Rte. 625 final, Arecibo; tel. 787/878-2612; www.naic.edu; admission $10 adults, $6 seniors and children).

Parque de las Cavernas del Río Camuy (Río Camuy Caves) (tel. 787/898-3100) contains the third-largest underground river in the world. It runs through a network of caves, canyons, and sinkholes that have been cut through the island’s limestone base over the course of millions of years. Known to the pre-Columbian Taíno peoples, the caves came to the attention of speleologists in the 1950s; they were led to the site by local boys already familiar with some of the entrances to the system. The caves were opened to the public in 1986. You need at least 2 hours for an adequate experience, but the more adventurous can take full-day tours exploring a part of the mysterious world with private tour operators.

Today, visitors explore most sites via the park trolley: a 200-foot-deep (61m) sinkhole, a chasm containing a tropical forest, complete with birds and butterflies and a huge water fall, and the entrance of Cueva Clara, the park’s premiere cave, a 45-minute odyssey through a fascinating underworld of stalactites and sculpted cavern walls. Tres Pueblos Sinkhole is 65 feet (20m) wide and 400 feet (122m) deep; it’s named for its location at the border of the towns of Camuy, Hatillo, and Lares (north at Km 2 on Rte. 129, from Rte. 111; tel. 787/898-3100; Wed–Sun and holidays 8am–5pm; admission $15 adults, $10 children 4–12; parking $3–$4, depending on vehicle).

Back down in Arecibo, a fun and interesting stop, especially if you are traveling with children, is the Arecibo Lighthouse & Historic Park ★ (Hwy. 655, El Muelle, Barrio Islote, Arecibo; tel. 787/880-7540; www.arecibolighthouse.com). Housed in a lighthouse built by the Spanish in 1898, this “cultural theme park” takes visitors on a history tour of Puerto Rico. But it’s a very tactile tour, where you can actually walk through many of the exhibits. It really interests kids; it definitely found the kid in us! The slave quarters were riveting, the mammoth pirate ship was thrilling, and then there was the pirate’s cave, with its alligators and sharks. Bring sun block, hats, and comfortable shoes and clothes. Tickets are $12 adults, and $10 children and seniors. The park is open 9am to 6pm weekdays and holidays, and 10am to 7pm on weekends. Parking costs $3.

Another unique place to visit while in Arecibo is the island’s last remaining drive-in movie theater. About an hour’s drive from San Juan, the Auto Cine Santana  (Exit 63 toward Rte. 2, left on Rte. 662; tel. 787/881-7869) is a family-owned business that has been keeping alive the tradition of watching movies under the stars since 1957. For just $3 per person, it is a great alternative for a night out. Snack bar selections go beyond your typical popcorn, candy, and soda to include alcapurrias and fried turnovers, and a variety of fresh fruit juices. The featured films aren’t usually blockbusters and are often dubbed in Spanish with English subtitles. The movie schedule is Monday, Wednesday, Thursday, at 8pm; Friday, Saturday and Sunday at 7:30 and 9:30pm.

Where to Dine

If you want to eat before heading back to the city, Arecibo is a good place, with several fine restaurants. The hands-down best, however, is the nearby Salitre Mesón Costero (Rte. 681, Km 3.8, Barrio Islote, Arecibo; tel. 787/816-2020). You can taste the salt of the sea in the breeze blowing through this charming oceanfront restaurant's terrace dining area and in the smacking fresh seafood served here. The dining room has big windows overlooking the coast and there's also a comfortable bar. This is a great place to watch the sunset. The house specialty, a kind of criolla version of the classic Spanish seafood paella, called mamposteado de mariscos, has mussels; shrimp; and freshly caught fish, octopus, or calamari. Its seafood-stuffed mofongo platters and the whole red snapper with tostones are hard to beat, but the mahimahi in parcha sauce came close.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.