The area is a plateau in form, of complex tectonic and morphological structure, subdivided by the river valleys. One of the main features is the Resava Cave. North of Resava Cave is the natural monument Lisine, which comprises two waterfalls, Veliko Vrelo and Veliki Buk. The Lisine hydro-complex and Resava Cave are under one administration. In 2017 the Government of Serbia and Institute for Nature Protection began preliminary actions into creating a new national park, which would cover the mountainous Kučaj-Beljanica region. It is supposed to be the sixth and the largest national park in Serbia encompassing the Resava Cave, Lisine complex and some of the oldest, intact forest in the country, like the Vinatovačarainforest, which remained intact since the mid 17th century.
Features
Sinking rivers
The karst region is location of numerous sinking rivers:
Kločanica; with the length of, it is the longest sinking river in eastern Serbia. It sinks into the abyss at an altitude of, flows underground for and resurfaces in the Resava valley, at an altitude of.
Klencuš; long, it sinks into the chasm at an altitude of and reappears after an underground flow of at an altitude of as the Zlot springs which form the river of Zlotska.
Velika Tisnica; it springs at the Beljanica mountain and is long. It disappears at, flows below the ground and springs out again at as Žagubica Spring. From there, it flows as the long Mlava river.
Nekudovo; long, sinks at and after springs out at as the source of the Crnica river.
Demizlok; it is long and goes underground at in the sinking cave. It resurfaces after at in another cave, Lazareva Pećina, which is the longest explored cave in Serbia.
Mikulj; long stream sinks at and after springs out at the Zlot springs.
Veliki Buk Watefall
Veliki Buk waterfall is located in the watershed of the Resava River in east Serbia. It is carved in the karst area, where the sinking river of Resava springs again from the ground in the canyon-type valley of Sklop. The waters springs from the karst spring Veliko Vrelo, forming a short stream of the same name which falls into the Resava. With the height of, it was considered the highest waterfall in Serbia until the 1990s when the higher waterfalls were discovered on the Kopaonik and in the Visok region of the Stara Planina. The waterfall is situated at an altitude of and east of Despotovac. It is formed on the tufarocks and the water falls into the deep lake. In August 2017 the waterfall was embellished with the color-changing decorative lights, becoming the first hydrology object in Serbia with such lights. The access roads are arranged with several restaurants but as of 2017 there is no mobile phone signal in the area, which the local tourist guides say is "probably a positive thing". There is also an stream water mill, "Mija's watermill" within the complex. It is built in 1918 and is still operational, though it is adapted into the tourist attraction, equipped with the objects from the century ago.
