Lake Vistonida forms a wetland unit with the Porto Lagos lagoon with which it is connected by a series of channels and canals, while it is separated from the sea by a narrow strip of land. The northern part of the lake has fresh water as three small rivers flow into it- Kosynthos, Kompsatos and Travos. Its southern part is brackish from the sea water that enters from Porto Lagos. The difference in the salinity of the water creates an ideal environment for a variety of fish species. In the coastal zone of the lake and in its marshy areas there is a rich flora with riparian forests, meadows, bushes and reed beds where many species of birds, various mammals, reptiles and amphibians live. Vistonida is famous for its birdlife. There are 260 species of birds of which nine are internationally rare or threatened, including White-headed duck, grebes, glossy ibis and pygmy geese. On the lake several species of herons can be found, in the northern area of fresh waters purple herons, little egrets and night herons, while in the southern area with brackish waters silver egrets, grey herons, white herons, cormorants and other waders and waterfowl.