Prášilské Jezero (Prášily Lake) lies on the slope of Poledník mountain ("Noon Mount" - 1,315 m), 1,080 m a.s.l., about 5 kilometres south-east of the small village Prášily and about 10 km south-west of the village Srní.

It is one of five morainic lakes in the Czech part of the Šumava mountains (Bohemian Forest). It is about 280 m long and 180 m wide lake with girth 730 m. The lake is 3.91 ha large and the deepest point is at 15 m. The moraine, which holds 275,000 cubic metres of water, is 9 m high. The rock face towers above the water level to the height 150 m.

This area along the border was forbidden for the public in the second half of the 20th century, during the communist era. Now it is protected in a nature reserve (about 158 ha large) together with Poledník mountain.

The red marked path from Prášily (4.5 km) leads to the lake. The access is also possible from the parking-lot which lies about 2 km east of Prášily (in the direction of the village Srní) along the yellow sign continuing along the green one and then the red one (about 4 km).