Thiersee, Natural monument lake in Tyrol, Austria

Thiersee is a 25-hectare lake at 616 m altitude in the Brandenberg Alps, up to 12 m deep, in a basin enclosed by the Maistaller Berg and Pendling. Twelve small streams feed it, and it drains via the 700 m Thierseebach into the Thierseer Ache. A promenade circles the shore, with a lido on the north bank and a campsite on the west.

The lake was first mentioned in documents in 1461 and 1474, when it belonged to local minor nobles. In 1751 the administrator of the Hofmark Mariastein sold it to the Baumann at Schröck, whose farm name gave rise to the earlier name Schröckensee. In 1775 it belonged to Matthias Hofer and was stocked with pike, tench, asp and carp for fishing. It was declared a natural monument in 1930.

The name Thiersee probably derives from the Middle High German word for wild animal, referring to the game-rich forests around the valley. From 1932 until after the Second World War, ice races and ski-joring behind motorcycles were held on the frozen lake, a use recalled by older residents of Vorderthiersee.

The lake lies at 616 m in the centre of Vorderthiersee and is reached by car or local bus from Kufstein through the valley. A lido with beach sits on the north shore, with rowing and pedal boats for hire; a campsite occupies the west shore. Water quality was rated excellent in 2016, and the lake is usually frozen from January to March.

Twelve small streams feed the lake, mostly from the Pendling massif, and its outflow, the 700-metre Thierseebach, runs to the Thierseer Ache and then the Inn. In the 19th and early 20th centuries the lake was also called Schröckensee or Schrecksee, after the Schröck farm whose owner bought it in 1751.