The main ridge covers an area of 2585 km2 of exceptional natural beauty - high peaks, many glacial massifs, 176 lakes. About 90% of these lakes are more than 2,100m above sea level. 119 of them were created by glaciers. The most famous of these are: “Popovo” lake, the “Kremenskite” lakes, the “Valiavihkite” lakes, the “Vlahinskite” lakes, the “Bunderishkite” lakes and the “Vasilashkite” lakes. The sharply contoured landscape and the blend of Central European and Mediterranean climates ensure a wide variety of flora and fauna. In 1962 part of the mountain range was proclaimed as a national park, initially named “Vihren” and later on renamed “Pirin”. Noting the uniqueness of the park and its global significance, UNESCO included it in the World Register of Natural Heritage.

The park covers an area of 26,479.8 hectares. It includes parts of the mountain range which are above 1000m above sea level with unique ecosystems, areas with specific geomorphology, a large number of Bulgarian and Balkan endemites and relicts. There are a few trees declared to be a natural heritage, including the “Baikusheva” white fir, more than 1200 years old, 16m high and with a circumference of 5.70m.

The park also contains 70 glacial lakes, many caves, waterfalls, majestic abysses and cliffs. The areas of natural beauty include the Bunderishki caves, Kasana, Kioshkata, the rock formation Pirostiata, the Demianishki Skok and Iulenski Skok waterfalls, the natural reserve “Baiuvi dupki - Jinjiritsa” etc. The mountains are almost impassable. Roads have been made from Bansko, Sandanski, Gotze Delchev etc.

The main ridge of the mountain is aligned from Northwest to South-Southeast. It is about 80 km long and 40 km wide.