Cueva del Hundidero

Cueva del Hundidero is a monumental karst cave in Montejaque, right at the heart of the Sierra de Grazalema Natural Park in Málaga province. It's one of Andalusia's most striking geological sights — the place where the Guadares River suddenly vanishes underground, only to resurface several kilometers away.

What will you see there?

The cave mouth looks like a giant collapsed amphitheater carved into the limestone. Over thousands of years, the Guadares River dissolved the rock, hollowing out a vast network of underground galleries roughly 4 km long. Water that disappears into the Hundidero doesn't reappear until it reaches the famous Cueva del Gato on the other side of the massif — an underground journey that explains the name "Hundidero," meaning "the place where things sink."

Right at the cave entrance stand the ruins of an abandoned dam, the Presa de Montejaque, also known as Presa de los Caballeros or Presa del Hundidero. Built in 1924 in a record nine months, it was at the time the largest barrel-vault dam in Spain and the first structure of its kind in Europe, reaching a height of 74 meters. The project turned out to be an engineering failure: the permeable karst bedrock let the reservoir's water seep away within hours. Despite repair attempts, the dam was eventually abandoned, and today its concrete silhouette offers a stark, post-industrial contrast to the wild landscape around it.

The whole area is protected as a Monumento Natural de Andalucía, underlining its outstanding natural and scenic value.

How do you get to Cueva del Hundidero?

The starting point sits by Montejaque, a small whitewashed village in the Serranía de Ronda, only a short drive from Ronda itself. A marked hiking trail leads to the cave — one of the region's classic routes, linking Hundidero to Cueva del Gato through a scenic canyon carved by the Guadares River. The walk suits anyone with average fitness, though sturdy hiking shoes and water are worth bringing, especially in summer.

When is the best time to visit?

Spring and autumn are the best seasons, when temperatures in the Serranía de Ronda are mild and river flow lets you fully appreciate the geological spectacle. In summer the rocky basin can get hot, though the cave's interior offers a cool retreat. In winter, after heavy rains, the water flow tends to be at its most dramatic.

Frequently asked questions

Can you go inside the cave? Reaching the main entrance and the dam ruins is possible on foot without special gear. Exploring the deeper gallery system, however, requires caving experience and equipment, so most visitors stick to admiring the impressive entrance and surrounding ruins.

What is the dam next to the cave? It's what remains of the 1924 Presa de Montejaque, an ambitious hydroelectric project that never worked because of the permeable karst ground beneath it. Today it stands as a valued industrial landmark and a highly photogenic stop along the route.

Is the trail to Cueva del Gato difficult? The path connecting the two caves runs through the Guadares River canyon and is moderately demanding — no extreme climbs, but good footwear and a sense of orientation help, particularly if you plan a one-way hike.

Where exactly is Cueva del Hundidero located? The cave lies within the municipality of Montejaque, inside the Sierra de Grazalema Natural Park in Málaga province, close to Ronda and the wider Serranía de Ronda.