Flood wall IJsselmeer.. No function anymore since it became a lake, before it was a lake it was actualy a sea (zuiderzee) southersea and it was directly connected to the noordzee (northsea), now there is a dike (afsluitdijk) between those sea's and turned the southersea into a freshwater Lake (IJsselmeer) History Historic Dike Water Lake Ijsselmeer Afsluitdijk Zuiderzee Noordsea Northsea Southersea Dutch Netherlands