Still one of the most important wetlands in the world, the refuge was named Wetland of International Importance in 1991, and for good reason. The Cold River (Rio Frio) is the largest flowing river in the area and is the main water source of Cano Negro Lake (Lago Cano Negro), a 2,000 acre (810 ha) lake that plays a crucial role for the environment. In the rainy season the rising water level invades the surrounding landscape, but in the dry season the water ebbs, exposing the dried out basin and the main channel of the Cold River which surges from the slopes of the Tilaran Mountain Range.

The delicate ecosystems found here supply a plethora of different plants and animal life, many of which are endangered or rare. More than 200 bird species can be found inside Cano Negro and its environment is especially vital for those species that migrate here from the north. Many of the fowl found here include anhingas, the captivating ibis, jabiru storks, the curious roseate spoonbill, a very large population of cormorants, northern jacanas, ducks and egrets.

Other wildlife such as jaguars, tapirs, deer, monkeys, caiman, turtles, snook, tarpon, and guapote find homes here. Also keep an eye out for sloths hanging from the trees above. With such a large and diverse fish population, anglers have a good shot at reeling in some trophies during fishing season which extends from July to March.

Throughout the dry months, February through April, the park can be easily accessed by road. During this time many of the swamps and wetlands dry up, transforming the layout of the refuge. The resulting lagoon filled basin attracts thousands of birds whose roar can often be confused with a jetliner as they fly overhead. During the rainy season boats are the main form of transportation as flooding causes many of the roads to be inaccessible for vehicles.

Many excursions are offered from the town of Los Chiles, 60 miles (96 km) north of Ciudad Quesada along Hwy 35. From there transportation into Cano Negro can be arranged. From La Fortuna head east towards Muelle, then north along Hwy 35 to Los Chiles.