Eider (river)

The Eider is the longest river in the German state of Schleswig-Holstein. Rising near Bordesholm, it flows generally westward, becoming navigable for sea-going ships from Rendsburg. Near its mouth, it is joined by the Nord-Ostsee-Kanal (Kiel Canal). The Eider flows into the North Sea at Tönning. For centuries, the Eider formed an important border between the Danish Duchy of Schleswig and the German Duchy of Holstein. The river's drainage basin is approximately 1,780 square kilometers.