The Großer Knechtsand is a large sandbank beyond the Weser and Elbe estuaries (in the Elbe-Weser Triangle) in the eastern part of Lower Saxony's Wadden Sea off the coast of North Germany.
The central area of the sandbank lies above the high water mark, forming the Hochsand of Hoher Knechtsand, which was formerly an island.
The Hochsand lies 11 km west of the village of Berensch on the nearest part of the mainland in the borough of Cuxhaven in the Land Wursten.
To enable the population of Heligoland to return to their home, the then Chancellor, Konrad Adenauer, offered the area around the Großer Knechtsand as an alternative site for military exercises.
This important area for resting and moulting shelduck and other seabirds was designated in 1957 as the largest German nature reserve in Germany.