Furna do Enxofre

Furna do Enxofre is a volcanic cave located on Graciosa Island in the Azores, Portugal. The cave features a large dome with a lake at its base where underground gases continuously rise and bubble through the water.

The cave was first documented by Prince Albert of Monaco in 1898 when he explored it using ropes to descend into its depths. This early exploration marked the beginning of scientific interest in the site.

The cave system serves as an educational center for geological studies, drawing researchers and students interested in volcanic formations and thermal activity point.

Access to the cave is through a tower with more than 180 spiral steps that lead visitors down to the entrance. Guided tours are offered at set times and provide the best way to explore the cave safely.

Inside the cave there is continuous release of carbon dioxide that makes the ground muddy and slippery. This ongoing activity shows that the volcanic region beneath the surface remains geologically active.

Location: Azores

GPS coordinates: 39.02459,-27.97247

Latest update: December 14, 2025 12:22