Gruta das Torres – the longest lava cave in the Azores

Gruta das Torres is a lava cave on the western flanks of Pico Island, in the municipality of Madalena. It lies outside the parish of Criação Velha at an elevation of around 300 metres. With an estimated length of more than 5.2 km, it is the longest lava cave in the whole Azores archipelago. Wikidata lists it as a natural monument.

What is a lava cave?

It is a geological formation of volcanic origin, created by the flow and cooling of underground rivers of magma. When the outer layer of a lava stream cools and hardens, the interior keeps flowing. Once it drains away, an empty tunnel remains. Gruta das Torres is exactly this kind of system: a group of interconnected lava tubes.

How did Gruta das Torres form?

The system grew from a series of pāhoehoe lava flows that came from the Cabeço Bravo parasitic cone roughly 500 to 1,500 years ago, which makes it very young in geological terms. Two types of lava, pāhoehoe and ʻaʻā, produced during different geological periods, took part in shaping the tubes. Pāhoehoe has a smooth, often ropy surface, while ʻaʻā is rough and jagged.

How big is the cave?

The tubes vary a great deal in size:

• width from 0.5 to 22 metres,
• height from 1.1 to 15 metres,
• total length of over 5.2 km.

This means a single system contains both narrow passages and large, tall chambers.

Who manages the cave?

Access used to be handled by the Mountaineering Association. Since 2011, management and organisation have been in the hands of AZORINA, SA. Because the cave is a protected site, it is worth checking the current visiting rules with this operator before you go.

Where is Gruta das Torres?

The cave is on Pico Island, in the municipality of Madalena, near Criação Velha. Its coordinates are about 38.497 N, 28.507 W. Pico is a volcanic island, and the cave fits well into a landscape shaped by past eruptions.

Frequently asked questions

How long is Gruta das Torres? It is estimated at over 5.2 km, making it the longest lava cave in the Azores.

How old is the cave? The lava that formed it flowed from the Cabeço Bravo cone about 500 to 1,500 years ago.

Who manages the cave? AZORINA, SA, since 2011.

What is its elevation? Around 300 metres above sea level.

Which municipality is it in? Madalena, on Pico Island, outside the parish of Criação Velha.