Volcán Azufral, Stratovolcano in Nariño Department, Colombia.

Volcán Azufral is a stratovolcano in the Western Ranges of the Colombian Andes, 12 km west of Túquerres in Nariño, reaching 4,070 m. Its summit crater holds Laguna Verde, a crescent-shaped lake 1,100 m long and 600 m wide at 3,970 m, colored green by sulfur and iron deposits, plus the smaller Laguna Negra and Laguna Cristal. Fumaroles remain active in the crater.

Azufral is the only volcano in Colombia's Western Ranges. Its name comes from the Spanish word for sulfur, azufre, and fumaroles still vent in the summit crater. The Reserva Natural del Azufral, covering 5,800 hectares, was created in 1990. After Galeras resumed activity, the Colombian geological survey (SGC, formerly Ingeominas) began monitoring Azufral and other volcanoes of Nariño and Cauca.

The name Azufral comes from the Spanish word for sulfur, azufre, after the fumaroles still venting in the summit crater. Local legend tells of two moons, a white one of peace and a red one of passion, that descended into the crater and gave the lakes their colors; every thousand years they are said to return, and anyone on the summit who keeps silent may hear them.

Access is mainly from Túquerres, 12 km east of the volcano, though the route from El Espino in Sapuyes offers greater natural variety. A road climbs to within 1.5 km of the summit, and the rest is covered on foot by trail. The Reserva Natural del Azufral, created in 1990, covers 5,800 hectares and entry is free.

Laguna Verde is a crescent-shaped lake 1,100 m long and 600 m wide, lying at 3,970 m in the north-western side of the crater. Its green tone comes from sulfur and iron-based deposits in the crater, not from algae. Two smaller lakes, Laguna Negra and Laguna Cristal, sit nearby in the same crater.