inside the mysterious flowstone cave `nebelhöhle` with stalagmites and stalactites in germany

ancient beautiful calcareous calcite cave cavern caving chamber column dark deep drapery erosion exploration exploring flowstone fog formation formations geology germany grotto hle hole inside interior karst limestone mineral mist mountain mysterious natural nature nebelhapara nebelhöhle old rock sonnenbafrac14 speleology speleothems stalactite stalactites stalagmite stalagmites stone structure subterranean swaibian tunnel underground wall wet