Who would have known that most of the Danube actually ends up in the Rhine and then in the North Sea…?! This is a sink hole where most of the Upper Danube river percolates through limestone and ends up a layer below which then resurfaces in the Ach source, which drains into Lake Constance and hence… the Danube ends up in the Rhine river!

Sign indicating the Danube sinkhole, Baden-Württemberg, Germany

Danube sinkhole in early spring, Nature Park of Upper Danube, Möhringen, Baden-Württemberg, Germany

Flood mark of the Danube, Möhringen, Nature Park Upper Danube, Baden-Wurttemberg, Germany