Lake Genval (, ) is an artificial lake in Belgium, southeast of Brussels near the Sonian Forest, which is a part of the municipalities of Rixensart, Walloon Brabant and Overijse, Flemish Brabant. A popular vacation and holiday destination, the lake is surrounded by turn-of-the-century homes built during the Belle Époque. On the lake's south is the Château du Lac, a five-star hotel, restaurant, and bar.