Achensee

Lake Achen (German: Achensee) is a lake north of Jenbach in Tyrol, Austria. It is the largest lake within the federal state, and has a maximal depth of 133 metres. Together with the Achen Valley it parts the Karwendel mountain range in the west from the Brandenberg Alps in the east.Water quality is near drinking water, with sight up to 10 m below the surface.

Pertisau is a small village on the Achensee Lake in the Tyrol region of Austria.Pertisau is in the Schwaz (district). It is located in the Karwendel Alpine Park, one of the oldest, cross-border, protected areas of the Eastern Alps.The town was used by English school story writer Elinor M. Brent-Dyer as the first setting for her Chalet School series, under the fictionalised name of Briesau am Tiernsee; a plaque on the wall of the village bookshop commemorates her writings.