Rila is the highest mountain in Bulgaria and the Balkan Peninsula. The relief is of alpine type, with stone ridges, towering peaks, deep precipices and numerous crystal-clear lakes (more than 140) and springs. The name of the mountain is thought to originate from a Thracian word signifying "rich in water". Three of the largest Bulgarian rivers spring from the mountain – Maritsa, Iskar and Mesta. The most alpine part of the mountain is located in the Northwestern region, although most of the highest peaks are in the Eastern region of the mountain. The central part is a declared National Park, including several natural reserves. Parangalitza Reserve and the region of the Seven Rila Lakes are the most visited and among the most attractive natural sites. At the foothills of the mountain in the town of Sapareva Banya are the hottest mineral springs in Bulgaria (103° C). Rila is famous with its winter ski resorts – Borovets, Malyovitsa, Panichishte, Semkovo, etc.