Traunsee is a lake in the Salzkammergut area in Austria. It is about 12 kilometres (7.5 mi) long. The lake is 3 kilometres (1.9 mi) wide and 191 metres (627 ft) deep. This depth makes it the deepest lake in Austria. It also is the second largest lake in Upper Austria.
View from Traunkirchen to Gmunden
|Primary inflows||Traun, Langbathbach, Pfrillenbach, Alte Traun, Rindbach, Eisenbach, Lainaubach|
|Max. length||12 km (7.5 mi)|
|Max. width||3 km (1.9 mi)|
|Surface area||2,435 km2 (940 sq mi)|
|Average depth||95 m (312 ft)|
|Max. depth||191 m (627 ft)|
|Surface elevation||422 m (1,385 ft)|
|Settlements||Gmunden, Altmünster, Traunkirchen, Ebensee|
At the north end of the lake is Gmunden, the capital of the Gmunden district . At the south end of the lake is Ebensee. The other two towns around the lake are Altmünster and Traunkirchen. At the east side of the lake is the mountain Traunstein. It is 1,619 metres (5,312 ft) high.
The first settlements around the lake go back to the fifth century. The Romans later called the Lake Lacus Felix (the happy lake). The first time the lake was mentioned in a document was in 909 AD. Then it was called Trunseo.
The Traunsee is a popular destination for tourists. It is possible to swim in the traunsee. The water quality is very good. The average water temperature in August reaches 19 °C (66 °F). Other water sports are also possible: Sailing, Surfing and Diving. 
On a small island in Gmunden is the Schloss Ort. It is a small, medieval Castle built in 1080.