The Republic of Poland is divided into 49 provinces (voivodships). The country is 312,520 km2 in area, and its total water surface covers 5000 km2 or 1.6% of the total area of the country. There are about 9300 lakes, covering an area of 3200 km2. For example, the Masurian Lake District has 1063 lakes, the largest of which have areas of about 11,000 ha. Lakes and artificial reservoirs have a capacity of 33 km3, and a large number of ponds hold an additional 1 km3. The two most important rivers in the country are the Vistula River (basin area of 194,000 km2), and the Odra River (basin area of 110,000 km2).