The biggest lake in the Balkans and also the only National park in which water and swampy ecosystems dominate. The northern swampy coast (20 000 ha) gives ideal conditions for development of wildlife, especially birds. There are also 50 species of mammals (the only water representative is otter), numerous amphibians, reptiles and insects. There is a very diverse vegetation in the lake as well as in its surroundings. During summer water lily and water heath pea (Trupa Longicurpa) meadows can stretch for kilometres.