Graciosa Caldera – Graciosa Island

The Graciosa Caldera is located in the municipality of Santa Cruz da Graciosa, on the Graciosa Island, classified by UNESCO as a Biosphere Reserve. Due to the enormous variety of important natural species in its territory, the Caldera is designated as a Regional Natural Monument.

The Caldera offers stunning landscapes, distributed within a circular depression of volcanic origin, measuring 1,600 meters in diameter and 350 meters in depth. It is situated where the summit of the volcano that formed the beautiful Graciosa Island once stood.

A Caldeira da Graciosa
Fotografia de João Leandro

Features

The Graciosa Caldera has two main regions: a polygenetic volcano covering 2 square kilometers, occupying the entire southeastern part of the island. Adjacent to it is a platform that gives rise to a basaltic region of 40 square kilometers, formed by 55 monogenetic cones.

The interior of the caldera features walls that have been smoothed at the base due to slope deposits.

History

The Caldera was formed approximately 12,200 years ago, linked to a significant hydromagmatic explosive event. After this event, there were four additional intra-caldera volcanic eruptions, notably an episode that involved the formation of an incandescent lake that filled the entire depression until spilling over the edge on the western side.

With this collapse, and subsequently the drainage from the lava side, the Furna do Enxofre was created.

Caldeira
Fotografia de Paulo Branco

Considering the date of the Caldera’s formation, it is believed that post-caldera eruptive activities have occurred in the last 10,000 years.

The Graciosa Caldera Volcano also exhibits secondary volcanic manifestations, particularly fumaroles located within the Furna do Enxofre and the Carapacho thermal springs and the Bay of Homiziados.

Furna do Enxofre

Inside the Graciosa Caldera, there is a volcanic cave known as the Furna do Enxofre or Sulphur Cave, which attracts many visitors due to its beauty. This fascinating cavern is characterized by its vaulted ceiling formed from low-viscosity lavas. Access is via a 200-meter tunnel that traverses the crater.

Túnel da Caldeira
Fotografia de Paulo Branco

Inside, there is a cold water lake and a degassing field formed by a continuous fumarole and ongoing emissions of carbon dioxide, which vary with environmental conditions. Its natural formation and rocks that resemble a gigantic face known as “The Guardian” of the cave enchant visitors, making this a must-see excursion.

Furna do Enxofre Visitor Center

To reach the Furna do Enxofre, visitors must first pass through the Natural Monument of the Graciosa Caldera, where the Visitor Center is located. This site offers a great opportunity to understand the volcanic formation that led to the creation of the cave and the Caldera.

Caldeira – Graciosa
Fotografia de Márcia Melo

The Visitor Center features various explanatory panels and monitors that assist visitors with very relevant information about the Cave and the Caldera.

Another option for nature lovers is to take a hiking trail that starts to the right of the road leading to the crater. The trail is a total of 5 kilometers long and takes about an hour and a half to complete.

This route leads to the highest point of the Graciosa Caldera, passing through a charming pathway lined with blooming flowers.

> Visit the Furna do Enxofre (information, prices, and hours)

Location on the Map

Video

With its lush green landscape, surrounded by Cryptomeria trees from Japan and heather, and an atmosphere that conveys tranquility, the beautiful Graciosa Caldera enchants all who pass by. It is undoubtedly an unmissable excursion for those who love to admire lush landscapes and venture into the depths of the Earth.

The Graciosa Caldera also offers visitors a panoramic view of Graciosa Island.