Lake Llanquihue, situated in the southern Los Lagos Region of Chile, is the largest and one of the best-known Chilean lakes. Osorno volcano stands on the southeastern shore of Lake Llanquihue and is one of the most active volcanoes of the southern Chilean Andes.
Lake Llanquihue (Lago Llanquihue) is the second-largest and, with neighboring Todos Los Santos, the best-known of Chilean lakes. It is situated in the southern Los Lagos Region, in the Llanquihue and Osorno provinces of northern Patagonia.
The lake has an area of about 330 sq mi (860 sq km) and is 22 mi (35 km) long and 25 mi (40 km) wide with depths of 5,000 ft (1,500 m). Puerto Varas, Llanquihue, and Puerto Octay lie on its shores and are popular resorts.
The lake's fan-like form was created by successive piedmont glaciers during the Quaternary glaciations. The last glacial period is called Llanquihue glaciation in Chile after the terminal moraine systems around the lake.
Osorno Volcano (Volcán Osorno) is a 2,652 m (8,701 ft) tall conical stratovolcano lying between Osorno Province and Llanquihue Province, in the Los Lagos Region of Chile.
Osorno sits on top of a 250,000-year-old eroded stratovolcano, La Picada, with a 6 km (3.7 mi) wide caldera.
Osorno is one of the most active volcanoes of the southern Chilean Andes, with 11 historical eruptions recorded between 1575 and 1869, including an eruption on January 19, 1835, which was witnessed by British Naturalist, Charles Darwin.
The basalt and andesite lava flows generated during these eruptions reached both Llanquihue and Todos Los Santos Lakes.
The upper slopes of the volcano are almost entirely covered in glaciers despite its very modest altitude and latitude, sustained by the substantial snowfall in the very moist maritime climate of the region. This mountain also produces pyroclastic flow, since it is a composite volcano.