Bulgaria has around 400 natural lakes with a total area of 95 km2 and volume of 278 million km3. The limans and lagoons along the Black Sea coast include from north to south Lake Durankulak, Lake Shabla, Lake Varna, Lake Beloslav, Lake Pomorie, Lake Atanasovsko, Lake Burgas and Lake Mandrensko. Of them, Lake Burgas is the most extensive with 27,6 km2 and Lake Varna has the largest volume with 165,5 million km3. The lakes along the Danube were dried to clear land for agriculture with the notable exception of the UNESCO World Heritage Site Lake Srebarna. There are 170 glacial lakes in Rila and 164 in Pirin. They are an important tourist asset. The most renown lakes include the Seven Rila Lakes, Popovo Lake, Banderishki Lakes, Vasilashki Lakes, Vlahini Lakes, etc. Swamps and marshes include Alepu, Arkutino, Aldomirovtsi Marsh, Dragoman Marsh, etc. There are around 2,200 reservoirs with a total volume of c. 7 billion km3. The largest ones are Iskar Reservoir, Ogosta Reservoir, Dospat Reservoir, Batak Reservoir, Kardzhali Reservoir, Ivaylovgrad Reservoir, Studen Kladenets, Koprinka Reservoir, Ticha Reservoir, etc.