Algar do Carvão is a volcanic cave located on the island of Terceira in the Azores, Portugal. Formed by volcanic activity, it features impressive stalactites and stalagmites, as well as a unique underground lake. The cave is a popular destination for tourists and nature enthusiasts, showcasing the geological wonders of the region. Visitors can explore the cave through guided tours, which highlight its geological significance and the diverse ecosystems within. The temperature inside remains cool and humid, providing a stark contrast to the island's warm climate. Algar do Carvão is a remarkable example of the natural beauty found in the Azores.