Plitvice Lakes National Park is a UNESCO World Heritage Site in the karst mountains of central Croatia, close to the border with Bosnia and Herzegovina, inscribed in 1979 for its chain of 16 surface lakes linked by travertine (tufa) barriers and waterfalls. The park was founded in 1949, covers 296.85 km² (about 90% in Lika-Senj County, the rest in Karlovac County), and its lakes step down 133 m from Prošćansko jezero in the south to Novakovića brod in the north, where the water leaves as the Korana river. The barriers that hold the lakes back are still growing, which is why UNESCO singled out the site for the undisturbed production of travertine, and why the park now limits summer entry to protect it.
How Moss and Calcite Build Plitvice’s Travertine Dams
Every lake at Plitvice exists because of a natural dam, and every dam is made of travertine, called sedra in Croatian. The process starts underground. Rain and snowmelt soak through the limestone and dolomite of the Dinaric karst and dissolve calcite on the way, so the springs that feed the park carry water heavily charged with calcium and magnesium bicarbonate. At the springs that water holds roughly twenty times as much carbon dioxide as the air, and while the carbon dioxide stays in solution, nothing settles out.
Downstream the water loses that gas: the Plitvica stream sheds up to 97% of its original carbon dioxide along its course, and once the water becomes strongly supersaturated (a saturation index above 3) and slightly alkaline (pH above 8), calcium carbonate begins to crystallise. It does so wherever the flow is slowed, aerated and sprayed, as on a ledge or a lip of rock. Mosses and algae growing on those ledges give the crystals a surface to cling to. Young moss shoots stay green and soft; older ones become encrusted with a yellowish layer and are finally petrified inside the barrier while fresh moss grows further out. Geologists call this plant-built rock phytogeneous tufa.
The role of the plants is subtler than was once thought. The botanist Ivo Pevalek, who began arguing for the protection of Plitvice in 1926, believed photosynthesis pulled the carbonate out of the water directly. More recent research says vegetation is not the main driver, but it still matters: algae and mosses remove carbon dioxide as they photosynthesise, which speeds crystallisation, and their tangled surfaces trap the deposits.
The results can be measured. The barriers grow by up to 13 mm a year in height, faster than erosion wears them down, and the floor of Lake Kozjak has been collecting about 0.8 mm of sediment a year for the past 3,000 years. Radiocarbon dates on the tufa show that the climate needed for this process has existed only since the end of the last ice age, some 12,000 to 15,000 years ago, and the tufa at the bottom of the lakes is thought to be 6,000 to 7,000 years old. The landscape is still moving: about 400 years ago Kozjak was two separate lakes, until the barrier at the Kozjak bridges outgrew a 40 m high barrier upstream and drowned it. That older barrier still stands underwater, its crest only 4 m below the surface. For more on how dissolving limestone shapes whole regions, see our guide to karst geography.
Sixteen Lakes from Prošćansko Jezero to Novakovića Brod
The water comes from the south, where the Bijela Rijeka (White River) and Crna Rijeka (Black River) meet at the village of Plitvički Ljeskovac. From there the combined flow, called the Matica, runs into Prošćansko jezero, the highest of the lakes. The total water surface is only about 2 km², and two lakes hold about 80% of it: Prošćansko jezero, 37 m deep, and Kozjak, 47 m deep. No other lake in the park is deeper than 25 m.
The lakes fall into two groups with different rock beneath them. The Upper Lakes (Gornja jezera) in the south sit on dolomite, a rock that is fragile when struck but lets little water through, so it holds broad, open lakes in a wide valley. In order, they are:
- Prošćansko jezero, named after the stake fences (prošće) farmers built along its shore
- Ciginovac, Okrugljak (“round lake”), Batinovac, Veliko jezero and Malo jezero
- Vir (“whirlpool”), Galovac, Milino jezero and Gradinsko jezero
- Burgeti, a chain of small, shallow pools whose name refers to the bubbling flow over the barriers
- Kozjak (“goat lake”), the largest, with Štefanijin otok (Stephanie’s Island) in the middle
Below Kozjak the character changes. The Lower Lakes (Donja jezera) lie on harder, more permeable limestone, and the water has cut a narrow canyon into it. The four Lower Lakes are Milanovac, Gavanovac, Kaluđerovac and Novakovića brod. Their names come from local tales: Kaluđerovac means “monk lake”, after a hermit said to have lived in a cave by the water, and Novakovića brod is “Novaković’s crossing”. Between them run the named cascades, including Jarkuše between Ciginovac and Okrugljak, the Galovački buk falls (about 20 m) below Galovac, and the Milka Trnina waterfall between Milanovac and Gavanovac, named in 1898 after the Croatian soprano who gave concert proceeds to build paths at the lakes.
The colours that draw photographers change with the minerals and organisms in the water and the angle of the sun, running from azure and green to grey and blue. The name Plitvice itself refers to the landscape: it was first written down in 1777 by Dominik Vukasović, the priest of Otočac, and comes from the Croatian plitko, “shallow”, after the shallow basins that filled with water.
Veliki Slap and the Birth of the Korana
The tallest waterfall in the park does not lie on the lake chain at all. Veliki slap, “Big Waterfall”, drops 78 m (256 ft) off the canyon rim where the Plitvica stream reaches the Lower Lakes. Its base, called Sastavci (“the confluence”), is where the Plitvica meets the water leaving Novakovića brod. From that point the combined flow is named the Korana.
The Korana is 138.6 km long and drains about 2,301 km². Counting the lakes and the Bijela Rijeka as its headwaters would add 13 km. Tufa forms along only the first 10 to 15 km of the Korana below the park, even though the water chemistry looks favourable further down. Downstream it forms a 25 km stretch of the border between Croatia and Bosnia and Herzegovina near Cazin before turning north.
The lowest point of the park, 367 m, is at the bridge over the Korana; the highest, Seliški vrh, reaches 1,279 m on Mala Kapela. That 912 m range, squeezed between Mala Kapela to the west and Lička Plješivica to the east, gives the park its mix of beech and fir forest, meadows and water. Rainfall averages about 1,500 mm a year, snow falls from November to March, and the lakes usually freeze in December and January (our page on the climate of Croatia sets this inland mountain climate against the coast).
The forest holds its own record. Čorkova uvala, a 79.5 ha patch of virgin forest in the north-west of the park, has beech and fir trees up to 700 years old. Brown bears, grey wolves and Eurasian lynx roam the park, which has about 50 mammal and 157 recorded bird species.
From the Emperor’s House to the 1979 UNESCO Listing
Tourism at Plitvice is older than the park. By 1861 a travellers’ lodge stood at Velika Poljana, known locally as the Emperor’s House because imperial officers stayed there. For the visit of Crown Princess Stéphanie in 1888, the lakes were laid out for visitors for the first time, and two paths still carry the names Stephanie’s Path and Dorothea’s Path. In 1893 Gustav Janeček, a Czech from Zagreb, founded a society to preserve the lakes and built a hotel.
The area was declared a national park in 1949, one of the oldest in Croatia. In the 1960s it became a film set: between 1962 and 1968 several adaptations, mostly German–French–Yugoslav co-productions, of Karl May’s Western novels were shot there, and Kaluđerovac stood in for the lake in Treasure of Silver Lake. In 1979 UNESCO inscribed Plitvice on the World Heritage List, at the same session as Dubrovnik and the Palace of Diocletian in Split, making them the first three Croatian sites while the country was still part of Yugoslavia.
Bloody Easter 1991 and the Endangered Years
Plitvice was a flashpoint in the break-up of Yugoslavia. On 28 March 1991 police of the Croatian Serb SAO Krajina seized the park and removed its Croatian management; a north–south road through the park linked Serb-held areas. On Easter Sunday, 31 March 1991, Croatian special police retook the area. Two men died: police officer Josip Jović, widely regarded in Croatia as the first casualty of the Croatian War of Independence, and Rajko Vukadinović, the first Croatian Serb combat fatality. About 400 tourists, most of them Italian, were evacuated. The clash is remembered as the Plitvice Bloody Easter, and a monument now stands where Jović was killed.
The Yugoslav People’s Army captured the park’s Croatian police station on 30 August 1991, and the area was then held by local Serb forces as part of the self-proclaimed Republic of Serbian Krajina. Hotels were used as barracks, Croats were driven out of the region, and landmines were laid around the lakes. UNESCO placed Plitvice on its List of World Heritage in Danger in 1991, and removed it in 1997 after restoration.
Twelve Thousand a Day: Plitvice’s Visitor Limits
The modern threat is popularity. Visitors rose to around 1 million a year and now hover around 1.5 million, almost 10% of everyone who visits Croatia. Waste water from hotels, illegal building around the lakes and farm run-off pushed nutrients into the water, driving the eutrophication that threatens the delicate process of tufa formation; the lakes are no longer drinkable. Swimming has been banned since 2006, and in 2018 UNESCO warned that the park’s World Heritage status was at risk.
In 2019 the management responded with a cap: in the summer months no more than 12,000 visitors a day, and no more than 600 people per entrance per hour. By 2024 the park director said the daily summer limit was the only real constraint, with spare capacity in spring and autumn; that year May and September drew more visitors than June. The wooden boardwalks are anchored into the travertine, which can crack the soft rock and cause seepage, so the park has proposed floating pontoon walkways in their place.
Plitvice is not the only place where flowing water builds its own dams: China’s high-altitude terraced lakes work on the same chemistry, as our guide to Jiuzhaigou Valley shows, and the white terraces of Pamukkale in Turkey are travertine laid down by hot springs.