Puyehue-Cordón Caulle, Stratovolcano in Los Ríos Region, Chile.

Puyehue-Cordón Caulle is a northwest-trending massif of coalesced volcanoes between Ranco Lake and Puyehue Lake in Chile's Ranco Province. Puyehue, a stratovolcano with a 2.4 km-wide crater, sits at the southeastern end; Cordón Caulle, a fissure ridge, lies in the centre; the Cordillera Nevada caldera is at the northwestern end. The summit is pale beige and grey, with forested lower slopes.

The Great Chilean Earthquake of 1960 triggered a major eruption at Puyehue-Cordón Caulle, demonstrating the connection between seismic and volcanic activity. Another large eruption occurred in 2011, sending an ash cloud that reached several neighboring countries.

Puyehue takes its name from Mapudungun puye hue, 'place of puyes', the small fish of the lakes below; Cordón Caulle comes from Kaulle, 'cahuil gull'. The massif stands between Ranco and Puyehue lakes, and its dacite, rhyodacite and rhyolite were carried by people to Pilauco Bajo around 12,500 to 13,500 years ago, where most of the stone artifacts are made of these rocks.

Route 215-CH from Fundo El Caulle provides access to paths leading toward observation points and geothermal areas. Weather conditions can change quickly, so warm clothing is advisable even during summer months.

The geothermal system reaches temperatures of 340 degrees Celsius (644 degrees Fahrenheit) in vapor systems, making the site a major focus for thermal energy research. The heat beneath the surface keeps several hot springs active, scattered around the complex.