The vast majority of the region is encompassed by the Black Sea drainage basin. The area includes all the largest rivers flowing in the country—Sava, Drava, Mura, and Kupa—except the Danube. The largest lakes in Croatia proper are Lake Dubrava and Lake Varaždin reservoirs, both near Varaždin, through which the Drava River flows. Croatia proper has a wealth of wetlands. Two out of the four Croatian wetlands included in the Ramsar list of internationally important wetlands are located in the region—Lonjsko Polje along the Sava and Lonja rivers near Sisak, and Crna Mlaka near Jastrebarsko. A high degree of karstification of the terrain in the Dinaric Alps has resulted in an increased permeability of soil and rocks and the formation of travertine barriers and waterfalls. The finest examples of the interaction of watercourses and karst are the Plitvice Lakes, listed as a UNESCO World Heritage Site, and Rastoke, to the north of the Plitvice Lakes.