Gosau Valley, Upper Austria, southwestern Salzkammergut region, valley of the Gosau stream. Lakes in the upper section of the valley: Vorderer Gosausee, alt. 937 m, length 1,8 km, width 500 m, depth 82 m; Hinterer Gosausee, alt. 1,156 m, length 800 m, width 600 m, depth 36 m. Lake Vorderer Gosausee is one of the best known mountain lakes in Austria. A dam has been built at the northwestern side of the lake, where the Gosau stream flows out of the lake. The water is supplied to a hydroelectric plant which provides electricity for the municipalities of Gosau and Steeg (on Lake Hallstatt). Lake Hinterer Gosausee is surrounded by majestic, steep rocky walls on the east and north. Between the two major lakes, at an altitude of 976 m lies the shallow Gosaulacke pool. From the lakes downward the Gosaul valley describe a semicircle and the Gosau stream flows into Lake Hallstatt near the Gosauzwang gorge (alt. 517 m).