The Mrežnica is a beautiful river in Croatia which is well known for its cascades and travertines. About 100 cascades can be found along its course of 64 kilometres. Foamy cascade barriers and travertines alternate with green lake-like parts. Decelerated by these barriers, the river is an excellent biotope for frogs, water snake and other animals. The Mrežnica is appreciated as a place to swim or for rafting tours in the beautiful scenery of untouched nature. Recreationists can admire water mills, whose primary function of grinding wheat or sewing wood has disappeared; their wheels do not produce flour, but they are exceptionally valuable as cultural heritage.