Algar do Carvão

Algar do Carvão is a volcanic chimney formed within the Caldeira de Guilherme Moniz on Terceira, created by lava draining from the interior of a magma chamber during an eruption estimated at around 2,000 years ago. The entrance tunnel descends 90 metres into a chamber of approximately 45 metres in diameter, where walls covered in stalactites of silica and iron oxide minerals create a visually striking underground environment. A small acidic lake occupies the lowest accessible point of the chamber.