Rila National Park is the largest national park in Bulgaria spanning an area of 810.46 km² in the Rila mountain range in the south-west of the country. It was established on 24 February 1992 to protect several ecosystems of national importance. Its altitude varies from 800 m. near Blagoevgrad to 2925 m. at Musala Peak, the highest summit in the Balkan Peninsula. There are 120 glacial lakes, including the prominent Seven Rila Lakes. Many rivers have their source in the national park, including the longest river entirely in the Balkans, the Maritsa, and the longest river entirely in Bulgaria, the Iskar. The national park occupies territory from 4 of the 28 provinces of the country: Sofia, Kyustendil, Blagoevgrad and Pazardzhik. It includes four nature reserves: Parangalitsa, Central Rila Reserve, Ibar and Skakavitsa.