The Montenegrin section of the lake and surrounding land have been designated as a national park, while the Albanian part constitutes a nature reserve and a Ramsar site.[1] The lake is a cryptodepression, filled by the river Morača and drained into the Adriatic by the 41 km (25 mi) long Buna (Serbo-Croatian: Bojana), which forms the international border on the lower half of its length.A characteristic feature of Lake Skadar's water balance is the high inflow from a number of temporary and permanent karst springs, some of which are sublacustrine in cryptodepressions (known as an oko).[4] Near the mouth of Rijeka Crnojevića, 11 m (36 ft) below the surface of the water there is a well-preserved wreck of the steamboat Skanderbeg sunk by partisans in 1942, during the Second World War.[1] Most authors agree that the Lake Skadar basin is of tectonic origin which had been formed due to the complex folding and faulting within north eastern wing of Old Montenegro anticlinorium (High Karst Zone).[1] The small range of many endemic species living in the Lake Skadar system together with ever increasing human pressure make its fauna particularly vulnerable.[1] Research of the phytoplankton community and chlorophyll-based trophic state indices show that the lake is on a betamesosaprobic level of saprobity, which means moderately polluted with organic compounds.