Lago Puyehue is an Andean piedmont lake situated on the border of Los Lagos Region and Los Ríos Region in southern Chile, within the Osorno and Ranco provinces. The lake measures 23 km in length and 11.5 km at its widest point, covering a surface area of 165.4 km². It sits at an elevation of 188 m above sea level, with an average depth of 76 m and a maximum depth of 123 m, holding a water volume of approximately 12.6 km³. The Gol-Gol River is its primary inflow, while the Pilmaiquén River serves as its outflow.

The main access point to the lake is via the town of Entre Lagos, a small settlement at the western end of the lake reached by a paved road heading east from Ruta 5, directly opposite Osorno city, approximately 47 km from the highway. From Entre Lagos, a road follows the southern shore eastward toward Nilque, which serves as a reference point along the route. The lake's name derives from Mapudungun, combining "puye" (small fish) and "hue" (place), reflecting the area's indigenous cultural heritage.

Kayaking and recreational fishing are explicitly noted as activities on the lake. The surrounding landscape is dominated by Andean Valdivian temperate rainforest, with Puyehue Volcano visible in the background. The broader area falls within or adjacent to Puyehue National Park, which protects over 107,000 hectares of forest, and the region is known for significant geothermal activity. Nearby attractions relevant to paddlers planning a visit include the Termas de Aguas Calientes hot springs, located before the national park entrance, and the Termas de Puyehue thermal center further along the southern shore road.

The climate in this area features rain throughout the year, with temperatures that oscillate between day and night. Aquatic sports are described as the most popular activity in the region. The lake is not characterized as a primary tourist destination in its own right, but it serves as a gateway to the national park and as a stop along the international route connecting Osorno to the Argentine border and onward to Bariloche via the Cardenal Antonio Samoré pass.