The reserve comprises the eastern slopes of the peaks of Golyam Rezen (2277 m), Malak Rezen (2191 m) and Skoparnik (2226 m), the northern slopes of Golyam Kupen Peak (1930 m), the upper valleys of Vitoshka Bistritsa and Yanchevska rivers. Its surface area is 1061.6 ha, the elevation is between 1430 and 2277 m.