Sils is a municipality in the comarca of Selva, in the Catalonia region of Spain. It lies in the province of Girona, in the northeastern part of the country.
The town is situated next to a former lake, which was drained in the nineteenth century. This drainage shaped the surrounding landscape on which the municipality now stands.
Sils is served by major transport links. The Autopista AP-7 and the N-II road both run through the municipality, and there is a Renfe railway station on the line between Barcelona and Girona.