Eichener See

The Eichener See, known in the Alemannic dialect as the Eiemer See, near Eichen in the Baden-Württemberg county of Lörrach is a periodic karst lake in the Southern Black Forest in Germany.

The lake, which only contains water when there is a high water table, lies in a hollow, a muschelkalk-karst basin. It has no surface inflow, its outflows are partly subterranean and partly through evaporation.

Source: Wikipedia