It is located in the Los Chiles and Guatuso counties, in the province of Alajuela, has an extension of 9.940 hectares.

It preserves one of the most important humid zones in the country, and it has international importance since it is the home of many migrant, endangered and commercial species.

Caño Negro is a sweet water lagoon, not to deep, with an extension of 800 hectares. The lagoon and the nearby areas, are some of most important and vital biological areas that support environment quality in the north side of the country.

Also this area is the habitat for a great variety of flora, fauna, and natural communities, many of which are unique or endangered. This gives a great international importance to the refuge.

The Caño Negro refuge is an important source of food to migratory birds from the north. There are also several species of plants and animals not found anywhere else in the country, birds and fishes for the human consume.