Algar do Carvão

The Algar do Carvão (Coal Cavern) is an ancient lava tube or volcanic vent in the Portuguese archipelago of the Azores, located in the middle portion of the island of Terceira. It is located in the municipality of Angra do Herosmo, under the civil parish of Porto Judeu. It is also one of the most beautiful caves in Portugal.

The cavern's presence has been known for a long time, but the cavern's depth and lack of ambient light made any descent difficult due to the vertical plunge, delaying any genuine research. It was feasible to re-examine the observations first-hand, including the most distant and tiny areas of the cavern, thanks to the invention of portable illumination systems. In the late twentieth century, the site was open to the public for weekly arranged tours (excluding weekends and holidays) throughout the summer (from May to September). Access to the location is also available through the Montanheiros (Mountaineers) organization, which is in charge of Algar-related problems.

Due to its unique volcanological properties and natural habitat, the 40.5-hectare area was designated as a Regional National Monument. The Algar's mouth consists of a 45-meter (148-foot) vertical entrance to the interior, which leads to a rubble and gravel slope. From here, a steep descent leads to the clean waters of the internal pool, which is about 90 meters (300 feet) below the level surface. The pool is fed by rainwater and can reach a depth of 15 meters (49 feet) during the summer months when there is little or no precipitation. The cave's silicate stalactites are notable for their unusual mineralogical properties.

Length: 100 m

Location: Terceira Island (Azores), Portugal