Algar do Carvão
Região Autónoma dos Açores
Algar do Carvão is a remarkable volcanic chimney located on Terceira Island, part of the Azores archipelago. Situated within the Guilherme Moniz Caldera, this natural monument allows visitors to descend approximately 100 meters into a vertical volcanic vent. Inside, one can observe unique silicate stalactites and a pristine underground lake, rare geological features that distinguish it worldwide. The Algar is part of a volcanic complex formed by ancient eruptions, including a significant basaltic eruption that shaped the landscape and lava flows extending several kilometers to the coast. The site lies about 550 meters above sea level and is encompassed by the Basaltic Fissural Zone, surrounded by volcanic massifs such as Santa Bárbara and Pico Alto. First explored in the late 19th century, it has since become a protected natural monument, attracting geologists and tourists alike. Its geological formations offer insight into volcanic activity and the island's evolution, making it a captivating destination for nature enthusiasts and adventurers.
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Tip: The best time to visit Algar do Carvão is during mild weather seasons to enjoy comfortable exploration conditions. Visitors should consider booking guided tours in advance as access involves descending steep volcanic terrain with specialized equipment. It is advisable to wear sturdy footwear and bring adequate lighting, although tours typically provide necessary gear. Discounts may be available for groups, students, or seniors, so inquire before purchase. Due to its protected status, follow all safety and preservation guidelines during your visit to help maintain this unique natural site.
Interesting facts
- •The stalactites inside Algar do Carvão are unique worldwide due to their silicate composition rather than the more common carbonate formations.
- •The underground lake within the Algar is noted for its crystal-clear waters, a rare feature in volcanic caves.
- •Lava flows from eruptions linked to Algar do Carvão extended up to 9 kilometers, reaching the coast of Terceira Island.
- •The Algar is part of the Basaltic Fissural Zone, a significant volcanic area surrounded by other volcanic massifs on Terceira Island.
History
Algar do Carvão formed within the Guilherme Moniz volcanic complex on Terceira Island as a result of a major basaltic eruption approximately 2,148 years ago, which produced extensive lava flows and shaped the current landscape.
Known since before 1893, early descents into the cave were limited by access difficulties and equipment.
The first recorded descent occurred on January 26, 1893, using only a rope.
More detailed explorations began in the 20th century, with significant organized descents starting in 1963 using specialized gear.
The site was later designated a Regional Natural Monument due to its geological and ecological significance, preserving its unique volcanic features and underground lake.
Place Guide
Volcanic Chimney~2000 years ago
A vertical volcanic vent approximately 45 meters high, expanded near its base, allowing visitors to descend deep into the volcanic structure and observe geological formations.
Silicate Stalactites
Rare stalactites formed from silicate minerals, unique in the world and distinct from common carbonate stalactites found in other caves.
Underground Lake
A crystal-clear subterranean lake located at the bottom of the Algar, formed within the volcanic cavity and contributing to the site's ecological uniqueness.
