Plitvička Lakes, continuous chain of 16 lakes and many waterfalls in western Croatia. The chain, 5 miles (8 km) in length, begins with two mountain streams that join near Plitvički Ljeskovac to form the Matica River. The river feeds Lake Prošće, the highest in elevation, and then flows by a number of waterfalls and smaller lakes into Lake Kozjak, the largest. Of the many cascades and falls, Plitvice and the Sastavci falls are the most spectacular, particularly during the spring snow melt. The lakes are the focal point of Plitvička Lakes National Park, which is also a nature reserve.