This otherworldly terrain of caves, sinkholes and limestone hills offers a chance to see one of the world's largest underground rivers.
At Rio Camuy Caves Park, you can take a guided tour of Clara de Empalme Cave and the Tres Pueblos Sinkhole. It's best to go early, since the number of tours is limited (there are no tours when it's raining). Open Wednesday-Sunday with tours every half-hour starting at 9 am, and the last tour is at 3 pm. Phone 787-898-3100.
About 40 mi/64 km southwest of San Juan.
