Čikola River, 46 kilometers long, is the longest tributary of Krka. What makes it unique is its diverse nature: it springs under the Svilaja Mountain nearby villages Mirlović polje and Čavoglave, continues to quietly flow through Petrovo polje (Petrovo field), and entering the canyon -in the last part of its course -it turns into a flood, sometimes forming small lakes, and following the canyon flows into Krka. Approximately 13 km of the water flow and the Čikola River Canyon - from the end of Petrovo Field to the border of National Park "Krka", has been protected as an important natural landscape since 1967.
The extremely attractive canyon - whose depth reaches up to 130 m, in which during winter a fast karst river flows and during summer vanishes leaving the canyon completely dry - provides many opportunities for hiking, rock climbing and canyoning. Flora and fauna of the canyon is made by 298 plant species, 4 fish species, 4 amphibians and 22 species of mammals, of which the most numerous are bats. Among several caves in the canyon, the most familiar one is Topla peć (Warm oven).
Traces of human presence dating from Paleolithic, around 18 000 years B.C., have been found in the canyon’s caves.
Čikola Canyon stretches from Town of Drniš to the mouth of the Krka River above Skradinski buk (Skradinski waterfall). Its beginning and end is bounded by two medieval fortresses: Gradina which dominates the view of Drniš and at the lower course of Čikola, Ključica fort.