The longest river in Schleswig-Holstein, the Eider was used in its eastern half in the 18th century for the construction of the Schleswig-Holstein Canal and is now taken up to a large extent by the Kiel Canal. Only shortly before Rendsburg, the Obereider separates from the channel and forms a wide lake. The Eider in the Obereidersee ends at the former Rendsburg old town island. Here, where once the port of Rendsburg ensured the cargo handling still create passenger ships and a waterfront promenade adorns the outskirts. From here you have an incomparable view of the panorama of the old town with the venerable St. Mary's Church and the small-scale tangles of houses. Right next to it, a modern marina invites pleasure boaters to stay overnight and stroll.
The Untereider has it very hard, without connection to Obereider, again in "ride" to come. It forms on the other side of the old town a calm waters with reed covered banks. From here, the river meanders at first parallel to the canal and begins to flow slowly again. An El Dorado for canoeists and nature lovers. Only through the Gieselau Canal with its lock, there is a connection to the Kiel Canal. From there, the Eider is also really navigable and invites many weekend trippers on a ride through lush meadows, along contemplative reed beds and kinkdurchzogener landscape. On the walks or bike rides along the many turns of this long river, you can see many wild birds that you hardly get to see. At the Eider barrier, which protects the landscape of the Eider from the ebb and flow, the water of the river leads into the North Sea.