1. Old San Juan. With its well preserved Spanish colonial-style architecture, Old San Juan continues to charm locals and visitors alike. Lively nightlife can be found in and around the city, and if you like a party atmosphere and live music, visit during “Las Fiestas de la Calle San Sebastián,” typically held in mid- to late January.
2. El Yunque National Rain Forest, Río Grande. This natural reserve is the only rainforest in the U.S. National Park Service. It comprises four different ecosystems and offers many hiking trails leading to waterfalls.
3. Las Cabezas de San Juan Nature Reserve, Fajardo. Kayak through mangrove channels leading to the bioluminescent lagoon, where the water lights up after sunset due to a reaction to movement from the dinoflagellates living in it.
4. Arecibo Observatory and the Río Camuy Cave System. These two attractions can be visited on the same day because of their relative proximity to each other – especially if you’re staying in the metropolitan area, since it will take over one hour of driving to reach them. The Arecibo Observatory is home to the largest radio telescope in the world, and although it’s more a research facility than a tourist attraction, around 100,000 visitors arrive each year. The Río Camuy Cave Park allows visitors to tour part of one of the world’s largest underground cave systems.
5. Bacardí Distillery. The Bacardí Distillery in Cataño offers free Monday-Saturday educational tours covering the history and processes of rum making. The tour lasts about 45 minutes. After a visit to the factory you can continue on to the ferry station, which takes you across the bay to Old San Juan for the amazing price of fifty cents (plus you avoid the hassle of parking in San Juan).
In addition, off the coast of Guánica to the southeast, you can visit Gilligan’s Island and Cayo Ballena for a day of snorkeling along mangrove channels and cays, as well as the tropical DRY Forest, which can begin with the scenic drive to Caña Gorda beach. Vieques and Culebra islands off the northeast coast should also not be missed. They offer some of the most beautiful beaches in the world, spectacular snorkeling and scuba diving, and magical bioluminescent bays.