Kamačnik is a 3.2-kilometer-long right tributary of the Dobra River. Its estuary is south of Vrbovsko, not far from the railway station, and a catering facility has been built at the estuary. From here, a very attractive canyon part of Kamačnik, about one kilometer long, begins for visitors. The Kamačnik gorge, deeply cut into the carbonate rocks, is characterized by a series of rapids, whirlpools and smaller waterfalls that form a winding web of shaded passages. A landscaped footpath equipped with wooden galleries and bridges leads through the canyon.
The source of Kamačnik is at an altitude of 405.4 meters above sea level, and the confluence with the river Dobra at about 370 meters. The part of the flow between the source and the canyon differs from the lively stream in the canyon part, which is calmer and the sides are milder. The reason for this is the differences in the geological structure of the substrate. In the canyon part, a larger slope of the riverbed is expressed, which increases the visual attractiveness of visitors due to the large number of cascades through which water flows and the steep narrow sides of the canyon. The opposite of this is the calm flow of the river, small gravel deposits and a milder relief upstream towards the source.
Kamačnik flows into Dobra with a smaller waterfall because it is blocked by a gap at the entrance to the canyon. On the west side rises a thickly layered limestone rock, and the initial part of the canyon and the whole area are overgrown with lush forest. Several picturesque spruces have been planted along the access road leading to the ruins of the walls of a large sawmill.