The water reservoir on the Nisa River in the middle of Jablonec nad Nisou was completed in 1910. It is the largest urban water area in Central Europe and it is used in particular for recreation nowadays.

The beaches are grass or sand, the access to the water is - depending on the particular point - easy to very steep. In the near vicinity, there are beach volleyball grounds, playgrounds, yachting, diving, boat rental, water bikes and other sports equipment, windsurfing, children's corners and concrete-covered grounds for football, tennis or basketball (all of these are free of charge).

There are several snack bars and restaurants.

Area: 42 hectares.