This Wildlife Refuge, with 9.969 hectares, consists of the Caño Negro lagoon, the Frio River and swamps. The whole ecosystem protects important migratory birds, several species of reptiles, like the caiman, and a large variety of fish, such as those  locally called  “Guapote”, “Gaspar” (supposedly prehistoric), “Mojarra” (basslike) and “Sabalo”(shad).At the refuge there is drinking water, restrooms, picnic and camping  grounds, electricity and telephones. In the town of Caño Negro, boats and horses can be rented.
The most attractive and favorite trek is along the Muelle-Los Chiles route, continuing on a boat ride along the Frio River to the refuge. These tours are available in the town of La Fortuna or directly through the Tilajari Hotel in Muelle.