Cueva del Sidrón Partial Nature Reserve

El Sidrón is the largest Asturian cave in non-carboniferous limestone, but the main interest of this cave also lies in its biological values, as it serves as a refuge for five species of bats and has two new species of coleoptera. The cave also has a prehistoric site with some cave paintings and numerous Neanderthal human remains have been found, the most important find in Asturian prehistory.

The Cueva del Sidrón, located in the foothills of the Sueve, is a karstic complex that opens up in Cretaceous limestone and Tertiary conglomerates, with ten known entrances that are grouped into different sectors: the Tumba Sector, which includes the Tumba cave and sinkhole; the Cabañina Sector, comprising the Cabañina cave and sinkhole and the Sidrón caves; the Aura wells and the Salelagua Sector, with the Salelagua cave and resurgence.

The total topographical development is distributed in three levels: the upper level, without water circulation, and made up of entrances and elevated fossil galleries; the intermediate level, located from the Tumba to Salelagua, is made up of a main gallery with a sinuous route, with varied morphology and different sections. Finally, the lower level is only accessible in short sections, and is crossed by two watercourses between the sinkholes and the Salelagua resurgence.