Plitvice Lakes National Park is one of the oldest national parks in Southeast Europe and the largest national park in Croatia. In 1979, Plitvice Lakes National Park was added to the UNESCO World Heritage register. The national park was founded in 1949 and is situated in the mountainous karst area of central Croatia, at the border to Bosnia and Herzegovina. The important north-south road connection, which passes through the national park area, connects the Croatian inland with the Adriatic coastal region.
The national park is world famous for its lakes arranged in cascades. Currently, 16 lakes can be seen from the surface. These lakes are a result of the confluence of several small rivers and subterranean karst rivers. The lakes are all interconnected and follow the water flow. They are separated by natural dams of travertine, which is deposited by the action of moss, algae, and bacteria. The particularly sensitive travertine barriers are the result of an interplay between water, air and plants. The encrusted plants and bacteria accumulate on top of each other, forming travertine barriers which grow at the rate of about 1 cm (0.4 in) per year.
The lakes are renowned for their distinctive colors, ranging from azure to green, grey or blue. The colors change constantly depending on the quantity of minerals or organisms in the water and the angle of sunlight.