Cueva de Pozalagua

Cave of Pozalagua

Useful Information

Location: Karrantza, Las Encartaciones, western Bizkaia.
Classification: SpeleologyKarst cave
Light: LightIncandescent Electric Light System
Dimension: L=100 m, W=60 m, H=20 m.
Guided tours: V=30.000/a.
Bibliography: I. Martínez-Arkarazo, M. Angulo, J.M. Madariaga, J. Les (): Preliminary Research on an Innovative Cleaning Process for Anthropologicaly Originated Microflora in Pozalagua Cave (Karrantza, Bizkaia).,
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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1957 cave discovered during quarry works.
1991 developed, electric light, opened to the public.
1998 new innovative light system installed.


Cueva de Pozalagua is located in the limestones of the Peñas de Ranero. The entrance is located in an abandoned dolomite quarry. The cave is a single huge chamber, 60 m wide, 110 m long, and up to 20 m high. This chamber is filled with an abundance of speleothems, stalagmites, stalactites, columns, shawls and curtains. But the highlight are numerous helictites, found all over the chamber. They talk of the biggest concentration of helictites in the world.

Another interesting fact about the cave is a recent restoration project. At this time the industrial era of this area ended and tourism increased, and so a number of institutions tried to optimize the countries touristic infrastructure, which included a Restoration and Classification Plan for the Pozalagua area. An initial survey of the cave revealed, that the original light system produced a lot of light and heat which resulted in the growth of lampenflora. So, after less than a decade, the cave already suffered from various damages. They were of course less than the damages of an unprotected cave, which is subject to vandalism and looting. And a good sign was the stable climate, which shows that the cave is able to handle 30.000 visitors per year.

The first change was the renovation of the light system, powerful lamps were replaced by cold lamps, which emitt much less infrared light. This also resulted in a reduction of electricity consumption by 30%. The innovative lighting systems tries to light the cave very uniform and during the tour the light slowly becomes darker, which gives the eyes time to adapt.