Vieta, Latgale
Čertoka ezers (Valnezers), also called Velnezers, is a small suffusion lake at the center of a roughly 55-hectare dabas liegums (nature reserve) in Šķeltova parish, Krāslava municipality, part of the Natura 2000 network. The lake formed in a sinkhole and has an unusually deep, funnel-shaped basin reaching about 18 meters, yet covers only 1.9 hectares and has no inflowing or outflowing stream. It sits amid dry pine forest with patches of transitional bog, and swimming is prohibited to protect its clear water.