a mountain massif in southwestern Bulgaria; the southern spurs are in Greece. The Pirin Mountains extend from northwest to southeast between the valleys of the Struma and Mesta rivers. They are about 75 km long, with elevations to 2,914 m (Mount Vikhren). The mountains are composed primarily of granites, crystalline schists, and marbles. Alpine-type peaks occur in the north. The interfluvial areas have become. peneplains, and the steep slopes are strongly dissected by canyons and river valleys. There are numerous hot springs at the foot of the mountains. The annual precipitation reaches 600–1,000 mm; there is abundant snowfall in the winter. Mountain forests are found at elevations to 2,000 m (oak, hornbeam, and beech in the lower zone; primarily pine in the upper zone). Higher, there are pine and juniper woods and mountain meadows. Logging and animal husbandry (sheep and cattle) are pursued. The area includes the Vikhren National Park (Bulgaria). Tourism is important.