Wandse (in sections also called Eilbek) is a river of Schleswig-Holstein and of Hamburg, Germany.The Wandse rises west of the village of Siek in Kreis Stormarn in Schleswig-Holstein and ends in the center of Hamburg in the Alster. Along the banks of the Wandse there were many water mills. The river passes through the settlements of Siek, Braak, Stapelfeld, and Hamburg.