Algar do Carvão is located inside a dormant volcano, consisting of a 90-meter-high volcanic cone, and also contains a beautiful lagoon of crystal clear and tranquil waters, some 100 meters deep. It would have originated in the great eruption of Pico Alto that launched lava at a great distance. Subsequently, another basaltic eruption began the process of forming another volcano, the Pico do Carvão. It is undoubtedly the best known volcanic cavity in the Azores and has become the first with reception conditions for visitors.