The Achensee lake is the biggest and most beautiful of all Alpine lakes in the Austrian Tyrol. The lake stretches for 8 kilometers long and 1-2 km wide. The water in the Achensee is very clean, the water clarity is around 10 meters deep, on the qualities of drinking water is nearly. The depth of the lake at the maximum point -133 meters. Since the lake is situated in the mountains, the water rarely warms above 20 degrees. Due to the size and winds of the Achensee is a favorite destination for Windsurfing skiing and sailing.

In the winter the water level in the lake drops to 6 meters, respectively, the size of the lake is constantly changing. At maximum level, the reservoir can store 66 million cubic meters of water.

The tourism in this region began to develop in 1859, when the railway was built. The first steamship "St. Joseph" was launched in 1887, and the second steamer "St. Benedict" appeared after only 2 years, in 1889.

In 1911 a new passenger boat "Stella Maris", designed for 400 passengers and is equipped with a quiet diesel engine, similar to those which were later used in submarines in the First World war. Nevertheless, the "Stella Maris" was difficult to maneuver. In 1959, "St. Benedict" was replaced by a modern ship with the same name and a diesel engine.

Since the lake is situated in a conservation area, boats and boats with gasoline engines is prohibited. In addition, since the beginning of 1970-ies on the lake began competitive swimming. Thus, there were established numerous sailing clubs. Currently, the lake often hosts national, European and world Championships in sailing.