Cueva El Soplao (sector de Herrerías) Nature · Herrerías, Saja-Nansa, Cantabria The galleries of the El Soplao cave-mine, famous for its eccentric aragonite formations and its Cretaceous amber deposit, extend beneath the municipalities of Rionansa, Valdáliga, and Herrerías. It was discovered in the early 20th century during work at the La Florida mines and opened to tourism in 2005. Photo: María Jesús Tomé (CC BY 2.0) What to see and do in Herrerías