Furna do Enxofre – Graciosa Island

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.

Túnel da Caldeira
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.

A Caldeira da Graciosa
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.

Caldeira – Graciosa
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.

Furna do Enxofre Visitor Center

Opening Hours

OCTOBER 1 – MAY 31
Tuesday to Friday: 10:00 AM to 5:00 PM;
Saturdays: 2:00 PM to 5:30 PM;
Closed on Sundays, Mondays, and holidays.

JUNE 1 – SEPTEMBER 30
Open daily from 10:00 AM to 6:00 PM.

Guided Tours

OCTOBER 1 – MAY 31
Tuesday to Friday: 10:30 AM | 2:30 PM | 3:30 PM;
Saturdays: 2:30 PM | 3:30 PM.

JUNE 1 – SEPTEMBER 30
Daily: 11:30 AM | 3:00 PM | 4:30 PM.

Tour Duration: 40 to 60 minutes.
Maximum number of people per tour: 30.

Price

Full Ticket: €3.50
Family Ticket (2 adults with children up to 17 years): €6.

Discounts:
Children (up to 12 years): free
Youth (13 to 17 years): €1.75
Seniors (> 65 years): €1.75
Youth, Interjovem, and Student Cards: free
Parques Friend Card: If you are a resident of the Azores, check the conditions and join the program.

The ticket includes Personal Accident Insurance.
Children up to 12 years must be accompanied by an adult.

Furnas de Enxofre
Fotografia de andreia almeida

Photographs

Photos by SIARAM

You can also take a path on the right side of the road leading to the crater, heading southeast for approximately 5 km. This walk, which lasts about an hour and a half, takes you through a beautiful trail lined with flowers, arriving at the highest point of the Graciosa Caldera.

At 402 meters above sea level, you will be rewarded with a stunning view, overlooking vegetation covered by Japanese Cryptomeria and heather, part of the Forest Park.

Furna do Enxofre Video

The site brings incredible peace and tranquility for those who love to contemplate nature. Don’t miss visiting this fantastic place!