Cueva de Pozalagua Nature · Karrantza Harana/Valle de Carranza, Enkartazioak / Encartaciones, Bizkaia Karst cavity holding the greatest concentration of eccentric stalactites in the world, mineral formations that grow defying gravity. It is one of the most singular show caves in the Basque Country. Photo: Makeip (CC0) What to see and do in Karrantza Harana/Valle de Carranza