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 16 lakes are separated into an upper and lower cluster formed by runoff from the mountains, descending from an altitude of 636 to 503 m (2,087 to 1,650 ft) over a distance of some 8 kilometres (5.0 mi), aligned in a south–north direction.

The fastest north–south road connection within Croatia, the A1 Zagreb–Split, runs about 50 km (31 mi) west of the national park and thus circumvents the protected area.

[13] Using public transport the lakes can easily be reached by direct bus lines from Zagreb, Karlovac, Zadar or Split.

The particular geographic position of the Plitvice Lakes and the specific climate features contributed to the emergence of many natural phenomena and a rich biodiversity within this area.

The large difference in altitude in a narrow space between the mountains in the south and the Korana river in the north represents a significant criterion for biodiversity in this region.

About 30 km (18.64 mi) north of the lakes at the conflux of the Korana and Slunjčica rivers, right in the center of the town of Slunj, similar phenomena occur.

Measurements of carbon dioxide quantities in the water show that they correspond with continuous sedimentation processes in the Plitvice Lakes area.

[24] Mosses, algae and water plants play a major role in forming the unique landscape of the Plitvice Lakes and its tufa barriers.

[23] These effects are fostered by the millions of microscopically-small bacteria and algae that grow on such plants, which secrete mucus to which the first microcrystals of calcite adhere.

For the sustainable formation of tufa it is therefore imperative to protect this extremely sensitive area from excessively harmful human influence.

The low level of industrial development in the surrounding area, along with the early introduction of protective measures, means an almost untouched landscape has been preserved.

The Plitvice Lakes national park is heavily forested, mainly with beech, spruce, and fir trees, and features a mixture of Alpine and Mediterranean vegetation.

It has a notably wide variety of plant communities, because of its range of microclimates, differing soils and varying levels of altitude.

As a result of human interference the species Salvelinus alpinus and the North American rainbow trout have been introduced to this ecosystem.

The European chub (Squalius cephalus) and common rudd (Scardinius erythropthalmus), whose emergence may be attributed to climate change, have also been discovered.

[citation needed] Examples of some animals found in the national park: While other nature protection areas are located far away from any interference by man, the Plitvice Lakes have permanently been exposed to human influence in the course of history.

[10] In 1493, not far away from the Plitvice Lakes a decisive battle in Croatian history between Kingdom of Croatia (then in personal union with Hungary) and Ottoman Empire took place.

In 1527, the Croatian Parliament elected the Habsburg monarch Ferdinand, Archduke of Austria as the new king of Croatia in the hope of resources to ward off the Ottoman advance.

The entire population of the military frontier, particularly the so-called frontiersmen, had the duty to protect this area of permanent unrest and terrible destruction.

Farmers had to focus on securing the daily bread for their families in these dour times, which was accompanied by grave changes to nature.

However, some very significant meetings took place at the Plitvice Lakes during the Second World War, as for example the first secret regional conference of the League of Communists of Croatia (Croatian: Savez komunista Hrvatske, SKH) in 1940.

On June 14, 1943 one of the founding sessions of the National Anti-Fascist Council of the People's Liberation of Croatia (ZAVNOH) took place at Plitvice Lakes.

The park was held by local Serb rebels backed by Slobodan Milošević and the Yugoslav People's Army (JNA) as part of the self-proclaimed Republic of Serbian Krajina during the conflict and suffered some damage in the process, with hotels and other facilities being used as barracks.

As regards architecture, the region of Lika is well known for its low wooden houses with roofs made of rye straw or shingles.

[10] Up until the 20th century, social gatherings during the winter months, when no agricultural activities could be performed, called "prelo" represented a typical tradition of this region.

Local cuisine consists of drinks, such as slivovitz (Croatian: šljivovica), wine and coffee or dishes, such as soft cheese (vrhnje), polenta, pršut, paprika sausage, roasted suckling pig (odojak) or lamb (janjetina).

Comparable phenomena to those prevailing at the Plitvice Lakes exist at Rastoke (Slunj), at the Krka National Park, at the rivers Una and the Pliva in Bosnia and Herzegovina and at the Krushuna Falls in Bulgaria.

Calc-sinter formation processes that have not emerged along a river flow can be observed at the Mammoth Hot Springs within Yellowstone National Park (USA) or at Pamukkale in Turkey.

Also inscribed by UNESCO as a World Heritage Site, its landscape of cascading lakes is made up of high-altitude karsts shaped by glacial, hydrological and tectonic activity.