Refugio de Vida Silvestre Los Guatuzos, Nature reserve near San Carlos, Nicaragua

Los Guatuzos Wildlife Refuge covers 437.5 km2 of tropical wetlands, rainforest and wildlife refuge south of Lake Nicaragua and west of the San Juan River, in the Río San Juan Department. Twelve rivers cross the reserve, the most important being the Papaturro. It is Nicaragua's only internationally registered tropical wetland area, listed under the Ramsar Convention and catalogued by UNESCO as a biosphere reserve.

Los Guatuzos was catalogued by UNESCO as a biosphere reserve and is listed as a wetland of international importance under the Ramsar Convention. It is the only internationally registered tropical wetland area in Nicaragua. The refuge covers 437.5 km² of tropical wetlands, rainforest and wildlife habitat south of Lake Nicaragua and west of the San Juan River.

The reserve takes its name from the Guatuzos, an indigenous people who lived in this area before disappearing. The Papaturro is the most important of the twelve rivers crossing the refuge, and the Ecological Center of Los Guatuzos runs guided visits, excursions and lodging inside the park, alongside a butterfly farm, a turtle and caiman nursery and an orchid display of 92 species.

Visit during the dry season when waterways are easier to navigate and wildlife viewing is more comfortable. Boat trips from San Carlos take several hours, so plan accordingly with experienced local guides.

The gaspar (Atractosteus tropicus), an ancient fish with fangs and a long snout, lives in the refuge's waters and is rarely seen; it preys on other fish, turtles and crabs. The reserve also keeps a turtle and caiman nursery and an orchid display of 92 species.