The Krka River is perhaps one of the most scenic and certainly one of the most important for its scientific and biological research value of all the rivers in Dalmatia. The Krka River, the 22nd longest river in Croatia, has a freshwater length of 49 kilometers and 23.5 kilometers of brackish water. Beginning at the bottom of the Dinaric Mountains, about 3.5 kilometers from the base of Knin, it runs 22 meters below the waterfalls of Topoljski Slap, Veliki Buk, and Krcic Slap. During the winter, these flow swiftly and noisily into the Krka River, but slowly dry up and vanish in the heat of summer. In all, there are seven travertine waterfalls along its course that leave generous amounts of semi-crystalline limestone at their base and a number of tributaries that feed into the River including the Krcic, Kosovcica, Orasnica, Butisnica, and Cikola with Vrb. The waterfalls produce large quantities of water, an estimated annual flow of 55 cubic meters a second down the largest, Skradinski-buk, and this amount has been known to increase to approximately 300 meters after heavy rainfall. From a height of 242 meters, the Krka River with its waterfalls and tributaries is an amazing, natural karstic phenomenon.
Along the Krka River lies Krka National Park, an area of 142.2 square kilometers, of which 25.6 square kilometers are water, within the Sibnik-Knin County of Croatia. The Park begins at the medieval fortifications of Trosenj-grad and Necven-grad and ends at the Sibenik Bridge. It covers the area beside the river for two kilometers from Knin and Skradin and along the lower part of the Cikola River. After WWI, the first proposal to make this area a national park was introduced in 1948. One of the earliest environmental protection laws was enacted in Croatia to cover the Krka from the first waterfall at Bulusic-buk to Skradinski-buk, the last waterfall along its course. A short time later, the trout that were endemic to the River, were put under protection legislation, as well. After much discussion and eventual compromise with proponents of hydroelectric power systems on the River, it was agreed that the middle and lower parts would be set aside for a national park, leaving the upper portions for the production of hydroenergy. Today, Krka National Park encompasses almost two-thirds of the course along the Krka River, including most of the river lakes and the two largest cascades, Roski slap and Skradinski-buk. The River flows at sea level below Skradinski down to Sibenik and the Park now includes Lake Prokljan.
Since its inception as a National Park in 1985, it remains largely unchanged in its valuable preservation of the many natural ecosystems of the area. There is an incredible amount of interesting fauna such as fish, birds, amphibians, and reptiles that add to its attraction for biological research. It is estimated there are at least 17 species of fish in the freshwater section of the Krka River and one species of trout, in particular, is only found here.
A unique attraction of the Krka National Park and the Krka River is the small islet of Visovac, a green oasis about the size of one hectare in the midst of the water. Dating back to the 14th century, are a monastery, with a museum and art collection housing over 620 Turkish objects, and a small church. Vivosac is visited by many tourists seeking a respite from a lengthy trek through the Dalmatian rocky land and twice a year, on August 2 and 15, it becomes a pilgrimage center.
The Krka River and Krka National Park are regions of considerable scientific, cultural, and educational interest. They remain largely unspoiled, although they are now recognized as major tourist and sightseeing attractions in Croatia.