Map of Sovata: Ursu lake

Lake Ursu is the largest heliotherm lake in Romania. It was formed in a sinkhole instead of Lake Horca, which appeared in 1710 by the clogging of the ponor and disappeared in the spring of 1852, by its decreasing. Until 1875, in the sinkhole, there was a meadow, through which the stream Toplița flowed into the ponor and went down like a salty spring. At the end of the eighteenth century the locals deviated part of the upper course of the stream to have drinking water.
Lake Ursu appeared in 1875, when the floods clogged the ponor with haystacks and alluviums. The accumulation of fresh water gradually dissolved the rocks of salt, leading to the collapse of the wall separating the Auriu Valley from Toplita. Thus in 1879 Ursu Lake is supplied by two streams.
The lake reached its maximum surface in 1881. Today it has a length of 288m, a width of 130-210m and a depth of 19m, the average salinity of 256g / l. Solar rays pass through fresh water from the surface, and accumulate in salt water, continuously increasing its temperature. if the resort would be closed, the autumn temperature would reach 70 degrees! At the beginning of the summer season the lake temperature is 35-50 degrees, and at the end it drops to 25-30.