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. It lies between the islands of Mellum (which is 16 km (9.9 mi) to the southwest) and Neuwerk (11 km [6.8 mi] northeast). The central area of the sandbank lies above the high water mark, forming the Hochsand of Hoher Knechtsand, which was formerly an island.