Sima de Aradelas

Sima de Aradelas, the deepest cave in all of Galicia, lies hidden in the limestone hills near the village of Campelo, within the municipality of Folgoso do Courel in Lugo province. It sits inside the Montañas do Courel UNESCO Global Geopark — the first geopark of its kind in Galicia and the thirteenth in Spain, recognized in 2019 for its exceptional geological heritage.

What exactly is Sima de Aradelas?

Aradelas is a system of vertical shafts and passages carved into the limestone of the Serra do Courel range. It was first explored in 1972 by the Santa Clara and Montañeiros Celtas caving clubs from Vigo, who reached a depth of 120 metres the following year. Later surveys by the local Aradelas Speleological Club produced a full map of the cave in 1987, recording six shafts and a depth of over 142 metres.

The real breakthrough came in 2024. Around forty cavers from Galician and Asturian clubs ran a series of expeditions and uncovered more than two kilometres of previously unknown, untouched galleries, chambers and shafts. Inside, they found a turquoise underground lake nicknamed Hydra, along with a rich variety of formations — stalactites, stalagmites and columns. These discoveries confirmed Aradelas as the deepest and one of the most extensive cave systems in the region.

How do you get there?

The starting point is the village of Campelo, inside the Folgoso do Courel municipality, deep in the mountainous interior of the Serra do Courel. This is sparsely populated countryside with scattered settlements, so a car is the practical way to get around — the geopark's viewpoints, information centres and trails are spread across the whole Montañas do Courel territory rather than clustered in one spot. It's worth checking with the geopark's local tourist information points beforehand to plan the route to Campelo.

What will you actually see?

It's important to be upfront here: the inside of Sima de Aradelas is not open to casual visitors. Because of the difficulty and risk involved — steep vertical shafts, narrow passages, and the technical caving gear required — access is restricted to trained speleologists working with organised clubs and expeditions. That doesn't mean a trip to the area is pointless, though. Campelo and the wider Serra do Courel sit within the UNESCO geopark, which offers numerous viewpoints, hiking trails and interpretation centres dedicated to the region's geology, including the well-known Campodola-Leixazós geological fold, protected as a Natural Monument. The surface landscape — limestone outcrops and wild valleys — gives visitors the clearest sense of what lies underground.

When is the best time to visit?

Given the mountainous terrain of the Serra do Courel, spring and summer are the best times to visit, when trails are fully accessible and conditions favour hiking around the geopark. Autumn also has its appeal thanks to the changing colours of the forests, while winter can make some higher routes and roads harder to access.

Frequently Asked Questions

Can you enter Sima de Aradelas on your own? No. Access is limited to experienced speleologists affiliated with caving clubs, due to the technical difficulty of the terrain and the specialised equipment required.

How deep is Sima de Aradelas? The 1987 survey recorded six shafts and a depth of over 142 metres, and the 2024 discoveries added more than two kilometres of previously unknown passages.

Where is Sima de Aradelas located? In the municipality of Folgoso do Courel, Lugo province, Galicia, near the village of Campelo, within the Montañas do Courel UNESCO Global Geopark.

What can you see nearby if you can't go inside the cave? Viewpoints, hiking trails and interpretation centres across the Montañas do Courel geopark, including the nearby Campodola-Leixazós geological fold.