Furna do Enxofre

Sulfur Cave

Useful Information

Location: Caldeira da Graciosa, São Mateus, 9880-000 Santa Cruz da Graciosa.
Follow road to the southeast, signposted Caldeira, through tunnel to the end of the road. Near Canada Longa. Nearest bus station at Canada Longa, 40 min walk.
(39.024379, -27.972139)
Open: NOV to MAR Tue-Sat, Hol 9-12:30, 13:30-17.
APR to OCT daily 9-12:30, 13:30-17.
Closed 01-JAN, Easter Sunday, 25-DEC.
Fee: Adults EUR 5, Children (7-14) EUR 2, Children (0-6) free, Seniors (65+) EUR 2, Families (2+*) EUR 10, Residents free.
Classification: Speleologylava cave
Light: LightIncandescent Electric Light System
Dimension: L=194 m, W=172 m, VR=40 m.
Guided tours: self guided, St=183.
Bibliography: Rosalina Gabriel, Fernando Pereira, Sandra Câmara, Nídia Homem, Eva Sousa, Maria Irene Henriques (2006): Bryophytes of Lava Tubes and Volcanic Pits from Graciosa Island (Azores, Portugal), AMCS Bulletin 19 / SMES Boletín 7 - 2006 Book online
Address: Centro de Visitantes da Furna do Enxofre, Caldeira da Graciosa, São Mateus, 9880 Santa Cruz da Graciosa, Tel: +351-295-714-009. E-mail:
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


1898 visited by the oceanographer and geologist Prince Albert of Monaco.
1939 staircase into the cave built.


The caldera is the main sight on Graciosa, the second-smallest island of the Azores. And this because of the Furna do Enxofre, a big cave inside the crater of a volcano. The caldera is located at the south-east end of the island. It has a diameter of 1,200 m and numerous caves, of which the Furna do Enxofreis the biggest. There are numerous thermal springs and solfatares, some inside the cave.

The road from Canada Longa goes through a tunnel into the crater to the cave entrance. The caldera also contains a picknick and barbecue area. The Furna is located at the end of the road, in the south-eastern corner of the caldera, just below the highest point of the rim (402 m asl). From the parking lot a winding stairway leads 100 m down into the cavern, built of local rocks at the cavern wall. You reach a huge dome, 130 m in diameter, 80 m high with the huge opening on one side where you came down. It is recommended to visit the cave between 11 and 14, as the sunlight shines through the entrance shaft at this time, and lights up the whole dome.

This cave is known for some time, and has a certain reputation among geologists. The oceanographer and geologist Prince Albert of Monaco visited the cave in 1898. He sailed across the Atlantic ocean, just to see this cave. And to get in he had to climb down the 100 m over a rope ladder. The staircase of today was built much later.

The staircase was built in 1939, and it allowed the farmers of the area to fetch water in the cave lake for their livestock. The staircase was very expensive, it costed 14,000 Escudos.

The source of the water was the Styx lake, impressive 130 m in diameter and 15 m deep. Later, when the cave was used as a show cave, a wooden boat allowed a fantastic boat trip on the lake. But today the boat lies on the shore and is leaking. The water level of the lake sinks continuously and hot steam and sulfuric exhalations make it very dangerous. Today the lake is enclosed at some distance. Still, a visit to the cave is worthwhile.

A last word: do not mix up the Furna do Enxofre with the Furnas do Enxofre on Terceira. The later are sulfuric springs without any cave.

Visited in the 19th century by Prince Alberto of Monaco and the naturalists Fouqué and Hartung. In 1879 whilst on a oceanological expedition to the Azores, Prince Alberto visited this cave. He was lowered down the entrance shaft on a rope.

The cave consists of a perfectly arched passage about 40 m high and 194 m long. This is a typical lava cave, formed by the molten lava draining out of a cooling mass. The best time to visit the cave is between 11.00 and 14.00 when the sun shines through the narrow funnel like entrance and lights up the interior with its abundant plant life. In the 20th century a staircase enclosed within a 37 m high tower was built inside the cave, providing easy access for the athletic visitor. At the base of the stairway is a lake of warm sulphurous water called the Furna do Enxofre from which the cave takes its name.

Text by Tony Oldham (2002). With kind permission.