Lake Črno jezero lies between Osankarica and Veliki vrh in the Pohorje Mountains, about 1,200 metres above sea level. Although surrounded by bogs and spruce forest, the lake is not entirely natural. Around 150 years ago, the Črnava stream was dammed to provide water for transporting timber downhill. Today, the lake forms part of Pohorje's protected natural landscape.
Its name, meaning Black Lake, refers to the dark organic sediment on the lakebed. Over time, decaying plant matter and other organic material have accumulated below the water, giving it an almost black appearance. Peat mosses grow around the shores, where wetlands meet dense spruce woodland. The area belongs to the Natura 2000 network, protecting Pohorje's sensitive habitats.
A marked trail from Trije kralji reaches the lake in about 40 minutes, covering 2.7 kilometres. A shorter approach is available from Osankarica. Wooden boardwalks protect the fragile bog ground and allow visitors to view the lake without walking across its vegetation. The walk can continue towards the Pohorje Battalion battle site, associated with the history of the Second World War.