The Río Encantado Protected Area (RENPA) is located in the northern limestone or karst region of Puerto Rico, one of the three main land forms (geomorphologic provinces) of the island’s geology. The Karst Waters Institute selected the karst region of Puerto Rico as one of the 10 most endangered karst ecosystems in the world, and each year, up to 1 square kilometer of limestone rock is lost due to gravel pit extraction. Habitat loss due to urban sprawl and industrial expansion make this loss significantly worse. As a result, karst ecosystems are being lost, endangering unique wildlife habitats and the most important underground aquifers in Puerto Rico.

The northern karst region of the Island has also been identified by federal and commonwealth conservation agencies as a priority conservation area, its tropical environment and geomorphologic evolution fostering the development of a unique natural area with high levels of biological diversity. The Conservation Trust of Puerto Rico identified a specific area within this region in order to focus its land conservation efforts: the Río Encantado Karst Interest Area (“Río Encantado”). Some 16,000 acres in size, this Karst Interest Area protects a unique and relatively undisturbed, roadless forested area, second in size in Puerto Rico to El Yunque National Forest, which is about 28,241 acres.

On August 2000, the Conservation Trust started acquiring properties from willing landowners within the Río Encantado Karst Interest Area. By 2010, the protection and conservation of a total of 1,818.18 acres through land acquisitions had already been achieved, thus constituting the lands that make up the RENPA. The Conservation Trust is actively working reducing the fragmentation between these properties, in order to achieve the significant contiguous protection of the Río Encantado Karst Interest Area into an extensive natural protected area.

The RENPA is host to the Río Encantado Underground River and Cave System, which represents one of the world’s longest continually traversable underground rivers at 10.5 miles (16.9 km), as well as Puerto Rico’s longest cave system. Río Encantado, along with the rest of the northern karst belt, represents some of the least disturbed karst habitats remaining in the Caribbean. The whole region is considered undisturbed wilderness, harboring the largest tract of continuous forest cover in all of Puerto Rico.