The geographical or geotectonics area of the Risnjak National Park belongs to the system of Dinaric mountains which represent the natural bond between the Alps and the Balkan mountains. It is a strong limestone area with very specific ecological, geomorfological and hydrological characteristics. The National Park has a complex structure of carbonate rocks whose formation date back to the Palaeozoic and to the Quaternary age. The oldest rocks from the Palaeozoic age are located in the upper flow of the Krašičevica and part of the Kupa River valley.
Rocks dating back to the Triassic period are located at the middle heights above sea level around Leska, Bela Vodica and Biljevina. Younger rocks from the Triassic and Jurassic periods are located on the higher areas of the Risnjak and Snježnik mountains.
The National Park’s relief is characterized by numerous limestone features such as dry meadows, underground stream caves, deep caves and limestone fields which are the result of climatic and hydrological effects. The area around the Risnjak and Snježnik mountains is representative of a typical forestal high limestone area in Europe.
The Risnjak and Snježnik mountain massifs represent a natural connection between the Alps and the Dinaric mountains and due to this fact are considered an important ecological corridor for plants and for large animals, such as the brown bear or wolf.