U Naděje Dam
Marenice, 471 56
It was built in 1938 to supply power for the sawmill in Hamr. The water used to flow to the sawmill through an 8-kilometre-long underground pipeline. The water area is 1.2 hectares; in summer, the water usually has an interesting green-and-blue colour. The conditions for swimming are excellent except that the water is often very cold. Not far from the dam, there is an ice cave, the only of this kind in Bohemia.