At the Zwischenahner Meer near Dreibergen
One of the numerous North German legends says that the creation of the Zwischenahner Meer was a work of the devil (Düwelswark).
According to the legend, the devil tried to prevent a church from being built in Oldenburg by disrupting the progress of construction and thus preventing the completion of the church building. The devil's idea was to simply fill in the church building. Following this idea, he tore up a large piece of forest near Zwischenahn with soil clinging to it and flew in the direction of Oldenburg in order to destroy the church with it. On the way to Oldenburg, however, the Düwel was so confused in its plans by three crowing roosters that it lost its direction. Shortly before the city limits, he dropped the torn piece of forest. This is where the small and large Wildenloh came into being, forest areas growing on sandy subsoil, which has amazed scientists to this day. And the spot where the forest was torn out filled with rainwater and today forms the Zwischenahner Meer.
Collapse of a salt dome is the cause of the formation
Legends and legends aside, the actual cause of the formation of the Zwischenahner Meer lies somewhere else, of course, as science has clearly proven. The Zwischenahner Meer is located above a salt dome as a remnant of the Zechsteinmeer from the Permian geological era about 250 million years ago. The formation of lakes could happen because the salt dome and the overlying overburden collapsed due to the leaching of salt from the groundwater. The Zwischenahner Meer was formed in the hole that was created in this way. Characteristic of lakes of this origin is usually a large depth in relation to the diameter. However, the Zwischenahner Meer is quite flat and therefore seems rather atypical. However, steeper edges can be detected on the Zwischenahner and Rostruper Ufer. However, they are greatly blurred by the thick layer of sludge at the bottom of the lake.