The Blue Lake is situated three kilometers away from the town of Baia Sprie, in the Maramureş County. It is the only lake in Europe that changes its colour according to the light and the amount of people who swim in it.
The Blue Lake was declared a natural reservation in 1977 and it is in the custody of the Administration of the National Park of the Mountains in Maramures.
It was formed after the collapse of an exploration mine on the Domnisoara dike between1919 – 1920, and the rain water has been gatheringthere along the years.Due to the leaching of the sulfurous compounds, the water is bluish green, sometimes with emerald effects.
The lake is 0, 5 hectares wide and almost circular in shape and it is situated on the south-west of the Mine Hill. It is 4 meters deep and the distance from one bank to the other is of 50 meters.
The pine trees around the lake give freshness and beauty to it.