Pirin in the context of "Rozhen Peninsula"

The Nestos (Greek: Νέστος [ˈnes̠tos̠]) or the Mesta (Bulgarian: Ме́ста [ˈmɛstɐ]) is a river in Bulgaria and Greece. It rises in the Rila Mountains and flows into the Aegean Sea near the island of Thasos. It plunges down towering canyons toward the Aegean Sea through mostly metamorphic formations. At the end, the main stream spreads over the coastal plain of Chrysoupolis and expands as a deltaic system with freshwater lakes and ponds forming the Nestos delta. The length of the river is 230 km (140 mi), of which 126 km (78 mi) flow through Bulgaria and the rest in Greece. Its drainage area is 5,184 km (2,002 sq mi), of which 66% is in Bulgaria. It forms some gorges in Rila and Pirin. The longest gorge between Pirin to the west and the Rhodope Mountains to the east is the 25-km long Momina Klisura in Bulgaria.

The Mesta's longest tributary is the Dospat (or Despatis). The banks of the river are covered mainly by deciduous trees that extend into halfway between Bulgaria and Greece where it forms the modern boundary of Greek Macedonia and Thrace, as well as the boundary between the Kavala and the Xanthi regional units, having first crossed the Drama regional unit. The river later forms a delta to the north where swamplands, wetlands and a lagoon once existed except in the east.

Melnik (Bulgarian: Мелник [ˈmɛɫnik], Greek: Μελένικο, Meleniko) is a town in Blagoevgrad Province, Southwestern Bulgaria, in the Southwestern Pirin Mountains, about 440 m above sea level. The town is an architectural reserve and 96 of its buildings are cultural monuments. With a population of 385, it is the smallest town in Bulgaria, retaining its town status today for historical reasons. It is situated on the foothills of the Pirin mountain range and is overlooked by the Melnik Earth Pyramids.

A ridge is a long, narrow, elevated geomorphologic landform, structural feature, or a combination of both separated from the surrounding terrain by steep sides. The sides of a ridge slope away from a narrow top, the crest or ridgecrest, with the terrain dropping down on either side. The crest, if narrow, is also called a ridgeline. Limitations on the dimensions of a ridge are lacking. Its height above the surrounding terrain can vary from less than a meter to hundreds of meters. A ridge can be either depositional, erosional, tectonic, or a combination of these in origin and can consist of either bedrock, loose sediment, lava, or ice depending on its origin. A ridge can occur as either an isolated, independent feature or part of a larger geomorphological and/or structural feature. Frequently, a ridge can be further subdivided into smaller geomorphic or structural elements.

Golyam Perelik (Bulgarian: Голям Перелик [ɡoˈʎam pɛrɛˈlik]) is the highest peak in the Rhodope Mountains, situated 19 km to the west of Smolyan. It makes the Rhodopes the seventh highest Bulgarian mountain range after Rila, Pirin, Stara Planina, Vitosha, Osogovo and Slavyanka. The peak is easily accessible, but currently cannot be climbed because a unit of the Bulgarian Army is stationed in its vicinity.

Perelik Point on Robert Island, South Shetland Islands is named after Golyam Perelik.

Abies × borisii-regis (Bulgarian fir) is a hybrid species of fir native to the mountains of the Balkan Peninsula in Bulgaria, northern Greece, Kosovo, North Macedonia, Albania and Serbia. It occurs at altitudes of 800–1,800 m (2,600–5,900 ft), on mountains with an annual rainfall of over 1,000 mm (39 in).

It is a large evergreen coniferous tree growing to 40–50 m (130–160 ft) (exceptionally 60 m (200 ft)) tall and with a trunk diameter of up to 1.5 m (4 ft 11 in). The leaves are needle-like, flattened, 1.8–3.5 cm (0.71–1.38 in) long and 2 mm (0.079 in) wide by 0.5 mm (0.020 in) thick, glossy dark green above, and with two blue-white bands of stomata below. The tip of the leaf is variable, usually pointed, but sometimes slightly notched at the tip, particularly on slow-growing shoots on older trees. The cones are 10–21 cm (3.9–8.3 in) long and 4 cm (1.6 in) broad, with about 150–200 scales, each scale with an exserted bract and two winged seeds; they disintegrate when mature to release the seeds.

The Melnik Earth Pyramids (Bulgarian: Мелнишки пирамиди) are rock formations, known as hoodoos, situated at the foothills of the Pirin mountain range in south-western Bulgaria. They span an area of 17 km near the town of Melnik, Blagoevgrad Province. Reaching a height of up to 100 m these sandstone pyramids are shaped in forms, resembling giant mushrooms, ancient towers and obelisks. They were formed primarily due to erosion from rainfall and bedrock wear. The Melnik Earth Pyramids are a geological phenomenon of global importance and were declared a natural landmark in 1960. The rock formations are home to rich flora and fauna heavily influenced by the Mediterranean climate. They are a tourist destination due to the natural environment of the area, the cultural sights of Melnik and the Rozhen Monastery.

Southern Bulgaria (Bulgarian: Южна България, Yuzhna Balgariya) is the southern half of the territory of Bulgaria, located to the south of the main ridge of the Balkan Mountains which conventionally separates the country into a northern and a southern part. Besides the Balkan Mountains, Southern Bulgaria borders Serbia to the west, North Macedonia to the southwest, Greece to the south, Turkey to the southeast and the Bulgarian Black Sea Coast to the east.

Geographically, the terrain in Southern Bulgaria is much more varied than that of the north, with the Upper Thracian Plain stretching in the east, while the south and west are dominated by some of Bulgaria's highest mountains such as Rila, Pirin and the Rhodopes, as well as smaller and/or lower mountains and valleys in the west, such as Vitosha, Belasitsa, Osogovo, the Sofia Valley, the Sub-Balkan valleys and the Kraishte region. Southern Bulgaria covers an area of 62,414 square kilometres and has a population of 5,085,872 as of 2009 (63% of Bulgaria's entire population), with a population density of 81.5 people per km. The three largest cities are the national capital Sofia, the largest city in Thrace, Plovdiv, and the major Black Sea port of Burgas.

U-shaped valleys, also called trough valleys or glacial troughs, are formed by the process of glaciation. They are characteristic of mountain glaciation in particular. They have a characteristic U shape in cross-section, with steep, straight sides and a flat or rounded bottom (by contrast, valleys carved by rivers tend to be V-shaped in cross-section). Glaciated valleys are formed when a glacier travels across and down a slope, carving the valley by the action of scouring. When the ice recedes or thaws, the valley remains, often littered with small boulders that were transported within the ice, called glacial till or glacial erratic.

Examples of U-shaped valleys are found in mountainous regions throughout the world including the Andes, Alps, Caucasus Mountains, Himalaya, Rocky Mountains, New Zealand and the Scandinavian Mountains. They are found also in other major European mountains including the Carpathian Mountains, the Pyrenees, the Rila and Pirin mountains in Bulgaria, and the Scottish Highlands. A classic glacial trough is in Glacier National Park in Montana, USA in which the St. Mary River runs. Another well-known U-shaped valley is the Nant Ffrancon valley in Snowdonia, Wales.