The mountain range is divided into four distinct parts. East Rila, known also as Musala Rila, is the largest and highest subdivision, situated between the valleys of the rivers Beli Iskar and Belishka. It is formed of two main ridges. The Musala Ridge spans in north-south direction between the valleys of Beli Iskar and Maritsa; the Ibar Ridge runs in west-east direction from the summit of Marishki Chal to the Avramova Saddle. It covers 37% of the mountain's territory and contains the highest summit in the range — Musala (2,925 m), as well as 12 of the 18 summits over 2,700 m — Irechek (2,852 m), Deno (2,790 m), Mancho (2,771 m) and others; there are 46 peaks over 2,100 m. East Rila contains a number of glacial lake groups, including Musala Lakes and Marichini Lakes, as well as the nation's largest ski resort Borovets.