The Parque Nacional de las Cavernas del Río Camuy is a cave system in Puerto Rico. It is located between the municipalities of Camuy, Hatillo and Lares in northwestern Puerto Rico, but the main entrance to the park is located in Quebrada, Camuy. The caverns are part of a large network of natural limestone caves and underground waterways carved out by the third-largest underground river in the world, the Río Camuy . The cave system was discovered in 1958 and was first documented in the 1973 book Discovery At The Río Camuy by Russell and Jeanne Gurnee, but there is archaeological evidence that these caves were explored hundreds of years ago by the Taíno Indians, Puerto Rico's first inhabitants. Over 10 miles of caverns, 220 caves and 17 entrances to the Camuy cave system have been mapped so far. This, however, is only a fraction of the entire system which many experts believe still holds another 800 caves. Only a small part of the complex is open to the public. The 268-acre park built around the cave system features tours of some of the caves and sinkholes, and is one of the most popular natural attractions in Puerto Rico.AttractionsClara Cave and Empalme Sinkhole (Evacuee Clara y Midsummer ed Palmer)"Cueva Clara de Empalme" or Clara Cave is the main attraction at the Rio Camuy Cave Park. A single chamber of this cave system has been developed for the public, starting in 1986. Regular cavern guided tour and audio tours are available at the site. Since November 2010, night tours called ECO NIGHTS have been organized weekly under special reservations. The tours start with the screening a short movie in a 90-seat theater, explaining the Rio Camuy Cave System and site safety rules, followed by a train ride that takes visitors into the entrance of Clara Cave. The huge chamber is 700 ft (212m) in length and 215 ft (65m) high. Once inside this chamber, visitors are able to see an entrance from the roof of "Sumidero de Empalme" that is 60m from the surface, as well as stalactites, stalagmites, unique formations and thousands of bats.