The Río Clarillo is a springtime creek run located in the Pirque sector of the Región Metropolitana de Santiago, approximately 45 kilometers from the city center. The river is notable for its crystal clear water moving over granite boulders — a characteristic that sets it apart from the more turbid glacial rivers common elsewhere in the Santiago area. The river runs through a north-south trench carved into an Andean granitic batholith, with the surrounding terrain ranging in elevation from roughly 850 meters to over 3,000 meters above sea level.

The river gives its name to the Parque Nacional Río Clarillo, which was originally established as a reserve in 1982 and elevated to National Park status in 2020. The park covers 13,085 hectares and is the first National Park in the Metropolitan Region. Under the National Park designation, activities that pose any risk to the environment or biodiversity are prohibited, and all visits are subject to strict conservation measures. Paddlers should verify with park authorities whether access to the river for paddling is permitted under current regulations before planning a trip.

Given its description as a springtime run, flows are likely seasonal and dependent on snowmelt, making timing critical for anyone planning a visit. The river corridor passes through habitat supporting condors, native foxes, and various bird species, and the area contains archaeological remains of cultural significance.