Deboyo Cave is located inside the Redes Nature Park Biosphere Reserve in the borough of Caso.
It is a 200-m-long karst cave traversed by the upper reaches of the River Nalón near the village of Les Llanes (near Campo de Caso). Interest in the cave rests on the fact that it is where most of the bats in the reserve nest, including the Mediterranean horseshoe bat, the riverbank bat and, to a lesser extent, the greater horseshoe bat, dwarf bat and cave bat.
