Lake Kozjak

Kozjak is by far the largest and deepest of Plitvice's sixteen turquoise lakes — a two-kilometre sheet of glassy water that acts as the natural divide between the Upper and Lower Lakes. Wooden electric boats ferry visitors from stop P2 to P3 across its emerald surface for free with a park ticket, giving one of the most memorable perspectives in Croatia as the towering wooded cliffs of Stubica and Gradinsko drop straight into the water. Kozjak is fed by a chain of waterfalls at its southern end and drains via the thunderous Milke Trnine cascade into the Lower Lakes. Look for the small forested island of Štefanijin otok near the northern shore — reportedly named after Habsburg Crown Princess Stephanie who visited in the 1880s — and for shoals of endemic Plitvice trout that thrive in the mineral-rich karst water. In winter, when tourist crowds vanish, Kozjak occasionally freezes solid enough for the park to open ice-skating on its surface, a rare permitted activity inside a UNESCO site. The gentle east-shore trail K takes ninety minutes end-to-end, mostly boardwalk, and is by far the least crowded of the Plitvice loops. Bring binoculars — bears, wolves and lynx all range through the surrounding beech forest and are occasionally sighted from the lake.