Cave of El Soplao

El Soplao is a karst cave located in Cantabria, Spain, renowned for its extraordinary array of speleothems, including helictites and curtains. Spanning 17 miles, the cave's formation began in the Mesozoic Era, during the Cretaceous period approximately 240 million years ago. Its discovery was incidental to mining activities, which provided economic support to local communities. Its geological significance was later recognized by speleologists, leading to its protection and development into a tourist attraction. El Soplao is home to unique underground formations like stromatolites and the mineral zaccagnaite-3R. Its cultural significance is highlighted by events such as music concerts held within. The cave is part of a larger system of over 6,500 caves in the region, reflecting its extensive natural and geological heritage.