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The Furna do Enxofre, also known as the Gruta do Enxofre (Sulfur Cave), is located in the southeast of Graciosa Island, in the Azores Archipelago.
This is a fascinating lava cave, and its main feature is its perfectly domed ceiling, formed by lava prisms.
Access to the Furna do Enxofre is through a 200-meter tunnel, crossing the entire crater. There is a 37-meter-high tower for entry into the interior, with a spiral staircase of 183 steps. Don’t worry about the number of steps—it will be worth the effort! See more details below.
Fotografia de Paulo Branco
Despite the large number of steps, it’s worth the journey, as inside you will find a cold water lake and an interesting degassing field, where fumaroles with mud and diffuse carbon dioxide gas emissions can be found, releasing gas in various areas of the cave floor imperceptibly.
When visiting Graciosa Island, this is a must-see destination, so don’t miss the Furna do Enxofre! The entire formation is natural, and you’ll also meet the “guardian” of the cave—rocks that form the shape of a giant with a face, right at the entrance.
History of Furna do Enxofre
The exploration of the Furna do Enxofre occurred in the 19th century, thanks to illustrious visitors who arrived in the Azores, such as Prince Albert of Monaco, along with naturalists Fouqué and Hartung.
This volcanic site is topped by the Graciosa Caldera, which has a diameter of 1.6 km and a depth of 350 meters.
Fotografia de João Leandro
The Caldera provides tourists with a perfect panorama of Graciosa Island and is classified as a Natural Monument of the Azores, a territory with important natural species that receive special protection. Experts have reported that the Furna do Enxofre is one of the largest volcanic caves in the world.
Additionally, the Furna do Enxofre is considered one of the main geosites in the Azores, making it an excellent option for tourists to appreciate an important historical landmark and venture into beautiful landscapes, descending into the Earth’s depths to explore this historic site.
Attractions
To reach the Furna do Enxofre, visitors must pass through the Natural Monument of the Graciosa Caldera, where the Furna do Enxofre Visitor Center is located (information on opening hours and pricing below), which is considered the core of the Biosphere Reserve and Graciosa Natural Park and serves as the access point to the Gruta do Enxofre.
Fotografia de Márcia Melo
At this support center, you can learn more about the volcanic formation that gave rise to the Furna do Enxofre and the Caldera, with informative panels and monitors displaying real-time gas levels detected inside the Furna.
Descending and visiting the Furna do Enxofre is a unique and unforgettable experience. The architecture is impressive, considered one of the most surprising calderas in the Azores. It is worth noting that the sulfur inside the cave is continuously measured to ensure visitor safety. If the level exceeds the minimum allowed, an alarm will sound.
