Sils () is a municipality in the comarca of Selva, in Catalonia, Spain. It is situated next to a former lake, which was drained in the nineteenth century. Autopista AP-7 and road N-II run through the municipality, and there is a Renfe railway station on the line between Barcelona and Girona.
Formerly a 7 km<sup>2</sup> lake, known as Llac de Sils or Estany de Sils existed close to this town, but it was desiccated in the 19th century and only a few residual wetlands remain. Presently some efforts are under way to try to reestablish a pond restoring a sample of the original vegetation.