Traunsee is a lake in the Salzkammergut, Upper Austria, Austria. Its surface is approximately 24.5 km² and its maximum depth of 191 metres makes it the deepest and by volume largest lake located entirely within Austrian territory; only Lake Constance on the border is deeper and bigger. It is a popular tourist destination, and its attractions include Schloss …Traunsee is a lake in the Salzkammergut, Upper Austria, Austria. Its surface is approximately 24.5 km² and its maximum depth of 191 metres makes it the deepest and by volume largest lake located entirely within Austrian territory; only Lake Constance on the border is deeper and bigger. It is a popular tourist destination, and its attractions include Schloss Ort, a medieval castle.