A lake with Mediterranean climate. The largest natural lake and one of the largest wetland areas in the Mediterranean part of Croatia. A refuge of endangered birds, and a wintering site for approximately one hundred thousand water birds. A lake paradise for anglers and cyclists, separated from the sea by a narrow limestone ridge. It is a special feeling indeed, to see so much diversity of waters at such a small distance. The sea right next to the lake? Or is it the lake right next to the sea? The description depends on which of those two forms of blue you prefer.
Lake and sea in closest vicinity – that is how we might describe Vransko Lake – the largest natural lake in Croatia. Immersed in the Mediterranean climate, but by no means deep – for the lake is two to five meters deep at the most – Vransko Lake is a natural phenomenon of a submerged karst field full of life.
In terms of its position and characteristics, the lake is truly a special phenomenon in Croatia, but also in a wider European area. It is a natural cryptodepression, a phenomenon creating a unique lake life.
Essentially, it is a geographical phenomenon in which the surface of water in the lake is above the sea level, while the bottom of the lake is below the sea level. Underneath a considerable deposit of sludge, which exceeds 20 meters in some areas, there is an impermeable flysch rock layer. It serves as a barrier preventing water from disappearing into the karst soil. A narrow karst ridge between the lake and the sea is another natural barrier protecting the lake. However, due to the porous nature of the ridge, seawater enters the lake and increases the salinity.
Life can be pretty noisy here, and you can clearly hear it in the sound of birds. The lake is a special ornithological reserve, after all, with over one hundred thousand water birds wintering in the area.
Due to the conservation of a substantial area of reed surfaces and endangered wetland habitats, the lake is an ornithological paradise. It is included in the list of Important Bird Areas in Europe, and the Ramsar List of Wetlands of International Importance.
The ecological value of the area is immense, abundantly providing everything necessary for the life of plants and animals, which can thrive in diversity.
The area of the Vransko Jezero Nature Park is partly covered by bulrush, sedge and reed, and it reminds of grasslands interspersed by shallow pools of water and flowers with butterflies flying around. There are also dragonflies and numerous insect species. The entirety of life present in the area is constituent part of the ecosystem that is equally dynamic throughout the year.
Bird lovers will undoubtedly cherish their visit an unforgettable experience. From hiding places, one can observe the life of birds, their nesting and care for the nestlings. The entire lifecycle is on display, for everyone to see. Vransko Lake is a treasure of ornithofauna, with 256 bird species recorded so far, over one hundred of them nesting in the territory of the Nature Park.
When it comes to nesting birds, four species present in the area are endangered at the European level, and seven species are endangered at the level of Croatia.
The lake is one of the few nesting sites of endangered species purple heron and pygmy cormorant in Croatia.
Ornithological reserve is the most valuable part of the Park in both biological and ecological terms. Many migrating birds rest and feed in the reserve during the period of migrations from cold European areas into warm African lands (and back).
Some bird species are present in the Park in large numbers, which is an indication of the fact that wetland habitats face increasing threats throughout Europe.
Subjected to destruction, perceived as undesirable, wetlands in Europe have decreased considerably in terms of surface. That is why Vransko Lake is a European oasis as well. The surface of Vransko Lake itself used to be larger in the past, with some wetland areas gradually transformed into fertile agricultural land by reclaiming, in order to plant vegetables and field crops. This land awards the efforts of people in the region of Ravni Kotari with good yields. A number of constant water sources, the sun and the mild nature of the Mediterranean climate provide ideal conditions for agriculture.
The water is abundant with fish. There is hardly an angler not acquainted with these waters. It is general knowledge that people come here to catch carp, catfish and pike – species that make this lake a fishing Mecca.
Eel, which is the only autochthonous fish species of the lake together with freshwater blenny, is strictly protected in the area of the Nature Park. This fish is a true natural phenomenon. It spawns in the distant Sargasso Sea in the North Atlantic. Small young eels travel towards our coast from that part of the world, using the warm Gulf Stream, eventually reaching Vransko Lake. Once they reach sexual maturity, they return to the northern waters, where they die upon spawning.
Brackish water provides habitat to a unique combination of marine and freshwater species, which makes the area highly attractive for fishermen globally. Vransko Lake is connected with the sea by a man-made channel of Prosika, which was dug out back in 1781, and connects the lake with the bay of Pirovac.
The passage was made in order to enable drainage of surplus water during the rainy periods, which was important in order to prevent flooding of the Vransko polje area.
However, the construction of the channel of Prosika brought certain biological and ecological changes to the lake. In the periods of lower water levels, for example, seawater flows into the lake to a higher extent, changing chemical and biological properties of water, and affecting the plant and animal world as well.
The lake receives its water from several sources. The most important ones are: Škorobić, Vrilo, Biba and Pećina. The sources of Pećina and Škorobić are located in the settlement of Vrana, which gave Vransko Lake its name.
Description of the lake in terms of numbers would be as follows: it is over 13 kilometers long, on average four meters deep, and its surface is approximately 30 square kilometers. The annual water level fluctuation does not exceed two meters, and the average fluctuation is one meter.
The panorama trail around the lake is forty kilometers long, which is why Vransko Lake is a destination of choice for many cyclists. Visitors who decide to enjoy a walk frequently stop at the little port of Prosika, enjoying the opportunity to rest in nature and gathering the energy to walk to the sightseeing point of Kamenjak, which awards visitors with a rare opportunity – a spectacular panorama of both the lake and the Dalmatian islands.
The specific position of Vransko Lake right by the sea is the source of all its attractions and its abundant biodiversity. The lake is surrounded by the Kosovac plateau, the ridge up to 110 meters high dividing it from the sea, and, a bit further away, there is also the Velebit Mountain, with its as yet insufficiently researched impact on the hydrology of the Nature Park.
The unique position of the lake has been attracting people since ancient times. It was appreciated and respected by the cultures of Liburnians, ancient Romans, Croats, Ottomans and Venetians, as can be seen in archaeological findings.
The lake, with everything that it offers, guarantees a special experience. Completely different and yet compatible landscapes are there for visitors who wish to experience the joy of spending time in nature. The sea and the islands, Mediterranean wetlands, rural heritage of the region of Ravni Kotari... It would not be wrong to conclude that Vransko Lake is a safe bet for demanding visitors, those who are hard to please, and who want to enjoy as many experiences as possible in one single, relatively small area. Such visitors will not make a mistake by coming here. However, Vransko Lake is also a good destination for those who do not like to plan everything in advance, because it is an unusually rewarding place, and a great starting point for exploration of surrounding areas. In a moment, one can visit a Dalmatian island, go back to fishing, with both marine and freshwater fish available – or take a break and enjoy the abundance of agricultural production of the area of Ravni Kotari.