breathtaking stalactite caves in the danube valley near beuron

alb beuron bische calcite cave cavern cavity column damp danube deep den donautal dripstone erosion formation geologic geology grow hle hollow journey leibertingen light lime maurushapara natural nature oberschwaben petershapara pillar reaction recreation rock sandstone schwacurren shadow sigmaringen stalactite stalagmite subterranean swabia time tour tourism travel tunnel upper vacation valley waddle water way wetness wildenstein