The main ridge of the mountain is aligned from Northwest to South-Southeast. It is about 80 km long and 40 km wide. It 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 2100m above sea level. 119 of them were created by glaciers. The most famous of these are: the “Popovo” lake, “Kremenskite” lakes, “Valiavihkite” lakes, “Vlahinskite” lakes, “Bunderishkite” lakes, “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 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 26479.8 hectares and is the largest in the country. It includes parts of the mountain which are above 1000m above sea level with unique ecosystems, areas with specific geomorphology, a large number of Bulgarian and Balkan indemnities and relicts. There are a few trees declared to be 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”.

The mountain is almost impassable. Roads have been made from Bansko, Sandanski, Gotse Delchev.