Azufral

Azufral is a stratovolcano located in the department of Nariño in southern Colombia, west of the town of Túquerres. It is the only volcano of the Western Ranges of the Colombian Andes. Its name derives from the Spanish word for sulfur, "azufre". The volcano is considered semi-dormant but there are numerous fumaroles in the summit crater. The summit of the volcano has an altitude of , and the north-western side of the crater contains a crescent-shaped lake named "Laguna Verde" () at . The lake is long and wide. and its bright green color is a result of the sulfur and iron-based deposits in the crater. There are also two other much smaller lakes in the crater, "Laguna Negra" () and "Laguna Cristal" ().
The volcano lies within a nature reserve, the Reserva Natural del Azufral, created in 1990. The reserve covers an area of and is free of charge to enter. As Azufral is semi-dormant, there are no restrictions on ascending the volcano and visiting "Laguna Verde": there is a road that climbs to within from the summit, and the remaining distance can be covered on foot via a trail.