The Lake of Sils is a wetland with unique characteristics in Catalonia. This singularity is due to the relatively humid climate and the thermal inversion of the bottoms of the jungle plain.

The diversity of aquatic habitats favors the presence of a rich and varied fauna. All of this means that Sils Lake, despite its small size, is of great importance in terms of biodiversity conservation.

Waterfowl are the most well-known and colorful inhabitants of the area. They breed several species of ducks, mallards, little martins and grebes. Among the fish, the presence of the spiny is remarkable, the only known population of the Tordera basin.

Every year millions of these birds make a long round trip from northern Europe to warmer areas where they spend the winter. That's when many stop at Estany de Sils.

There are lowland and mid-mountain meadows, meadows, willows and other riparian forests. There are also other habitats that are not typical of wetlands, such as Mediterranean meadows rich in annuals, basophils, cork oaks, holm oaks and carrascars, and Mediterranean pine forests.

Currently, the area has been equipped with three lookouts, an observatory tower, itineraries and informational signs.

An information center has been created at Sils RENFE station, with a permanent exhibition. In the area, the Biodiversity Foundation has also subsidized habitat improvement actions.