The Upper Sûre Lake (Luxembourgish: Stauséi Uewersauer; French: Lac de la Haute-Sûre [lak də la ot syʁ]; German: Obersauer-Stausee [ˈoːbɐˌzaʊɐ ˈʃtaʊˌzeː]) is a large reservoir in north-western Luxembourg. It is the largest body of water in the country. It gives its name to the commune of Lac de la Haute-Sûre, which was formed in 1979.A large reservoir in north-western Luxembourg, perfect for outdoor activities like hiking, biking, and water sports.