Seepages of the Danube
Between Immendingen and Möhringen as well as near Fridingen, water from the Danube seeps down into the river bed over a large area. The water of the Danube resurfaces in the Aachtopf spring about twelve kilometres away. It then flows as the Radolfzeller Aach into Lake Constance at Radolfzell. So a part of the Danube water also flows into the Rhine. This geographical situation is a striking feature of the Main European Watershed which separates the drainage basins of the North Sea and the Black Sea.