Crestasee (Romansh: Lag da Cresta) is a small lake shared by the municipalities of Flims and Trin in the Grisons, Switzerland. From 1892 a guest house on its northern end served as pension and still is a restaurant today in its original state.There is no tributary to the lake and whilst walking along its shores you may be surprised by finding the lake both sides of you, realizing, that the holes between the rocks lying around the lake are filled with water.