Haldensee, Alpine lake in Tannheimer Valley, Austria

Haldensee is a 73-hectare lake at 1,124 m above sea level in the Tannheimer Tal, lying between Grän and Nesselwängle and filling the whole width of the valley floor. Its northern and southern shores drop steeply, while the eastern and western ends are flat; the Gessenbach enters from the southeast and the Strindenbach from the southwest, and the Berger Ache drains west toward the Vils. The village of Haldensee stands near the west shore, Haller at the northeast end, and the Tannheimer Straße (B 199) runs along the north bank.

The sources record no medieval salt route at Haldensee; the lake lies about 1 km west of the watershed between the Vils and Lech, and its outflow, the Berger Ache, runs west to the Vils. The villages on its banks, Haldensee in the municipality of Grän and Haller in Nesselwängle, grew up on the valley floor beside it, and the Tannheimer Straße (B 199) now runs along the northern shore.

The lake lies between the villages of Haldensee, in the municipality of Grän, and Haller, in Nesselwängle; the western shore takes the name of the first. Bathers use the lido and campsite on the shore, anglers fish for perch, pike, carp and tench, and in winter a marked, groomed track crosses the ice from west to east on foot or skis.

A walking trail circles the lake starting from the Haller parking area with several viewing spots along the way. Winter visitors can enjoy ice skating and skiing activities nearby.

From January to March the lake is regularly frozen, and a marked, groomed track crosses it west to east on foot or on skis. The southern shore holds one of only two stone crayfish occurrences in Tyrol, possibly the result of artificial stocking rather than a natural population.