Śviciaź Lake, Natural lake in Grodno Region, Belarus.

Śviciaź is a freshwater lake in Grodno Region featuring clear water surrounded by dense vegetation and natural shorelines. The waters are bordered by various aquatic plants and reed beds that shape the lake's appearance.

The lake is karstic, formed when Quaternary deposits collapsed into underground voids. In 1930, through the efforts of Stanisław Lorentz, the lake and its surroundings were recognised as a monument. Since 1970 the lake and a surrounding forest of 847 hectares have been protected as the Svitzyazanski landscape reserve, upgraded to republican status in 2007 and run as a state nature-protection institution from 2012.

The lake's name is tied to a legend recorded by Adam Mickiewicz in his 1820–1821 ballad "Świteź": a town ruled by Prince Turan sank here rather than surrender to invaders, and its inhabitants became the flowers that kill those who pick them. A stone near the shore carries lines from the ballad. The rare lake lobelia, called "cary" locally, is the plant of the legend.

The lake is accessible via regional roads connected to main transportation routes through Grodno Region. Visitors should wear good footwear since the shores are natural and can be marshy in places.

The lake's most unusual record is a plant form, Tetradinium javanicum, otherwise described only from Java, and the mollusc Planorbis stelmachticus, known only from lakes in France, Belgium and Germany. Its water also holds relict crustacean species typical of northern lakes.