The 0.85 km² alpine lake is located 13km south of Grünau at an altitude of 589m. The catchment area of ​​the alpine lake consists of 35 square km. The maximum 5m deep lake has a water volume of about 2.1 million cubic meters and the water stays 10 days in the Almsee before it flows with an average of 2.4 m³/s flows in the river - Alm. Since 1965, the area around the alpine lake is a nature reserve. With its fascinating fauna and flora of the alpine lake untouched by construction boom spared. To ensure that this jewel in Austria remains continue to be so good please do not burn open fire, throw away any garbage, no tents or camping, take any plants and also surfing, sailing and diving is prohibited. Only the paddling and rowing is allowed in the period of 8-18 Clock.

The lake at the northern end of the Dead Mountains is max. 2.3 km long and 700m wide. By a huge landslide in the area Hetzau at the end of the Ice Age was the alpine lake. The maximum water temperature is also in the summer higher than 14-16 degrees and we see other than the swans and wild geese only some swimmers in the Almsee. In addition to the native fish species are mainly the well-known wild geese. The ethologist Konrad Lorenz spent much time on Almsee, where he made fundamental observations on them. The outflow of the alpine lake - Almsee is also the source of the river Alm. This river is one of the cleanest rivers in Austria and is therefore used for fish farming.