Being the site of the largest limestone massif in Europe means that besides being plentiful, the caves and underground systems are grandiose.

Systems such as those in Arañonera, Escuaín and Las Olas hold a number of European records for their length and the height of their chasms.

Several companies in Aínsa offer the chance of crossing mountains at their root, for all levels, and provide all of the necessary equipment. The only thing you will need is not to suffer from claustrophobia.