The natural landscape of Bulgaria is diverse, consisting of lowlands, plains, foothills and plateaus, river valleys, basins, and mountains of varying elevations. About 70% of the country’s territory is hilly land and 30% is mountainous. The average elevation of the country’s territory is 467 m, generally decreasing from south to north and from west to east.
In the central part of the country lies the Balkan Mountain Range, where the highest peak is Botev (2,376 m). From south to north, its western area is crossed by the Iskar River, which forms a picturesque gorge more than 70 km long. The northern arm of the Balkan Mountains is mainly karst. The highest peak in this range is Vasilyov (1,490 m).
To the south of the Balkan Mountains are the western Balkan valleys and the Srednogorie (central mountainous region). The largest valley in the southern arm of the Balkans is the Sofia valley, the location of the Bulgarian capital Sofia. The mountains in the Srednogorie are the Zavalsko-Planska Range, the Ihtimansko Srednogorie, the Sashtinska Sredna Gora, and the Sarnena Gora.
Between the northern arm of the Balkans and the Danube River lies the Danube valley, with an area of roughly 31,000 square meters. Its eastern part consists of plateaus – the Dobrudzha plateau, the Plovadia plateau, the Lilyak plateau, and the Shumen plateau, among others. To the north lie the Trans-Danube lowlands, which occupy the terraces of the Danube river.
To the south of the capital Sofia rises the mountain Vitosha, whose highest peak is Cherni Vrah (2,290 m). Its foothills extend to the middle part of western Bulgaria, where low-lying and medium-elevation mountains alternate, such as Ruy, Milevska, Zemenska, Konyavska, Verila, and others. West of the Struma River valley and south of Kraishteto is the Osogovo-Belasishka mountain range, which includes the peaks of Osogovska (Mount Ruen, 2,251 m), Vlahinska, Maleshevska, Ograzhden and Belasitsa (Mount Radomir, 2,029 m). The highest Bulgarian mountains are in the Rila and Pirin ranges, situated to the east of the Struma River valley. The average elevation of these mountains is 1,258 m, and 60% of their area is higher than 1,000 m. In Rila there are 31 peaks with an altitude of over 2,600 m. The highest peak on the Balkan Peninsula, Musala (2,925 m), is located there.
There are two peaks of over 2,600 m elevation in the Pirin range. One is Mount Vihren (2,914 m) – the second highest peak in Bulgaria and the third highest peak on the Balkan Peninsula. Beautiful alpine glacial lakes have formed in the circuses of these peaks.
The Rhodope Mountains are located to the east of the Mesta River valley and Rila. There are 11 peaks with an elevation of over 2,000 m there, the highest of which is Golyam Perelik (2,191 m). The many natural landmarks – caves, waterfalls, and alpine lakes – attract scores of tourists every year.
Between the Srednogorie, Rila, Rhodope and Black Sea are the Gornotrakiyska Lowlands, the Haskovo Foothills, the middle Tundzha river valley, the Burgas Lowlands and the Strandzha and Sakar mountain ranges. The eastern parts of the country border on the Black Sea, where beaches covering hundreds of kilometers attract Bulgarian and foreign tourists.
Bulgaria has a wide variety of minerals. According to the national records detailing the reserves and resources of Bulgaria’s mineral deposits, 163 types of minerals have been found in the country, 7 types of which are fuel and energy resources, 14 types are ore, 75 types are non-ferrous, and 67 types are viable as rock covering and construction material.
Bulgaria is located in the temperate continental latitudes, and its climate is favorable for the development of various types of tourism. The average annual amount of sunshine for the territory amounts to about 2,500 hours. The climate of Bulgaria is influenced by atmospheric associated with the Icelandic minimum, the Azores maximum, and the Eastern European maximum. Arctic and tropical air currents pass through the country in significantly rare cases. The average annual temperature in the country is between 10° and 14°С, with a predominant temperature between 11° and 12°С. This figure is greatly dependent on altitude. In the mountains, at higher elevations thermal conditions are influenced by the thinner atmosphere, so that over 2,300 meters above sea level the average annual temperature is below zero (Mount Musala – 2.9°С). In the lowlands and foothills Northern Bulgaria the lowest average monthly temperature is in January (-1.4° and -2.0° С), and in Southern Bulgaria (excluding the plains) the average January temperature is between 0° and 1-2°С. In the mountainous regions (1,000 – 1,200 m) and the plains, the average January temperatures are between –2° and –4°С. In the higher elevations, the lowest temperatures are recorded in February; the average monthly February temperatures are between -8° and -10°С. During this month Musala ha an average temperature of -11.6°С. Along the Black Sea coast, the average monthly temperatures in January and February are above zero. Along the country’s northern coastline, they are 0.8° – 2°С, and along the southern coastline they are 2.4 – 3.2°С. The highest average monthly temperatures are typically for the months of July and August. They range from 21 – 24°С. The regions outside the mountains to the north of the Balkans have an annual July temperature of about 22°С, and in the lowlands and foothills to the south temperatures range between 23° – 24°С. In the mountain regions (1,000 – 2,000 m) temperatures vary from 12° – 16°С, and over 2,300 meters, from - 5 – 8°С.
Rainfall is unevenly distributed throughout the country. There is a considerable deviation in average annual rainfall – from 500-550 mm in the Danube valley and the Gornotrakiyska lowland to 1,000-1,400 mm in the alpine regions. The annual snow cover in Bulgaria is unstable, and shows significant deviations both with regard to elevation and geographical location. In the lower parts of the country, the snow cover lasts from December to March, while along the Black Sea coast and in the territory south of the Balkan Mountains it remains for only a month, from January to February. Snow occasionally falls during other times of the year (in November or April, for example). But in these regions there is almost no permanent snow cover. Due to the frequent warming of air temperature to more than 0° С, the snow melts a number of times during the winter. Continuous and thick snow cover forms in the mountainous alpine regions. At an altitude of 1,000-1,500 meters, the snow lasts for 4-5 months, and over 2,000 meters - from 7 to 9 months.
The country climate can be divided into five distinct zones – temperate-continental, continental-Mediterranean, transitional, the Black Sea zone and a mountain zone. The favorable preconditions for winter tourism in our mountains include the substantial snow cover and the lower temperatures, allowing the snow to last longer. The development of recreational activity along the Black Sea coast is favored by the few rainy days during the active tourist season, abundant sunshine, moderate temperatures, the relatively high temperature of the sea water, and the lack of blustery winds. What’s more, the bracing mountain air and the coastal air saturated with iodine vapors are both beneficial. Our country is also rich in mineral water. Depending on the thermal level, the mineral springs are divided into cool springs (hypothermal with temperature of up to 20°С); warm springs (up to 20-37°С); and hot springs (hyperthermal with temperature of over 37°С). The cool springs are distributed throughout the country, in such locations as Narechen (Asenovgrad region), Shipkovo (Troyan region), Ovcha Kupel (Sofia), Smochan (Lovech region), Voneshta Voda (Gabrovo region), Merichleri (Simeonovgrad region), and other locationss. Thermal waters constitute the majority of mineral waters in Bulgaria. The spring with the highest temperature is the mineral spring in Sapareva Banya, the only geyser fountain in Bulgaria and in all of continental Europe (103ºС). The most famous thermal springs in the Balkan Mountain are in Varshets, Barziya, Montana, Lakatnik, Opletnya; in the Sofia region there are Bankya, Gorna Banya, Knyazhevo, Ovcha Kupel, Sofia, Pancharevo, and others; in the Srednogorie are Strelcha (40°С), Hisarya (49.5°С), Bankya (51.1°С), Pavel Banya (54.6°С), Starozagorski Bani (45.8°С); along the valley of the Struma River – Blagoevgrad, Simitli, Sandanski, Levunovo and Marikostinovo; along the valley of the Mesta River - Banya (56°С), Dobrinishte (43°С) and in the village of Eleshnitsa (56°С). In Bulgaria the most widespread kind of mineral water are the nitrogen-rich thermal waters, found at such places as Sapareva Banya, Simitli, Narechen, and Momin Prohod. Carbonated acidic waters are those flowing from the springs in Mihaylovo, Slivenski Mineralni Bani, and Stefan Karadzhovo; waters of high hydrogen-sulfide content are found in the Sofia valley. Half of the thermal waters show relatively high radioactivity, surpassing 15 emans/l – such as the Klisura spring (200 emans/l), the Strelcha spring (250 emans/l), and others. Particularly high radioactivity has been registered in the springs of Momina Banya (560 emans/l) and at one of the springs in Narechenski Bani (1,300 emans/l).
The small territorial range of Bulgaria and its close proximity to the Danube River and the Black Sea, together with the location of the Balkan Mountains and its proximity to the Aegean Sea are preconditions for short river arteries and small river systems. The Iskar River is the longest river in Bulgaria (368 km), which empties into the Danube River and has its headwaters in the Rila Mountains. Other large rivers that empty into the Danube river are the Lom, the Ogosta, the Vit, the Osam, and the Yantra. The rivers directly flowing into the Black Sea collect their waters from the easternmost parts of the Danube valley, the northern arm of the Balkans, the Balkan Mountains and Strandzha. These are the Batovska, the Devnya, the Provadiyska, the Kamchia, the Dvoynitsa, the Fakiyska, the Izvorska, the the Ropotamo, the Dyavolska, the Karaagach, the Veleka and the Rezovska Rivers. The largest Bulgarian river within the Aegean drainage basin is the Maritsa (321 km long, with an area of 21,084 square km). Other large rivers are the Arda, the Tundzha, the Mesta, and the Struma.
Bulgaria’s natural lakes (coastal, glacial, karst, landslide, by-river and tectonic) are concentrated along the Black Sea coast and the Danube, and in the alpine regions of the Rila and Pirin ranges. With reference to their location and hydrographic charecteristics, the coastal lakes are divided into three groups: the Dobrudzha lakes (Durankulak Lake, Ezerets Lake, Shabla Lake, Shabla Tuzla, Nanevo Tuzla and Balchik Tuzla); the Varna lakes (the Varna and Beloslav Lakes); and the Burgas lakes (Burgas Lake, Atanasovsko Lake, Mandrensko Lake and Pomorie Lake, Alepu, Arkutino and Stomoplo). The glacial lakes have formed as a result of the glacial activity during the Quaternary period in the Rila and Pirin ranges. There are roughly 260 such lakes. They occupy the bottoms of the circuses, circus terraces, and trough valleys, and they are located at an altitude of 2,000-2,600 meters. The highest is the Gorno Polezhansko Lake in the Pirin (2,710 meters above sea level), and the lowest is Lokvata Lake (1,858 meters above sea level). The longest is Gorno Ribno Lake in the Rila range (801 m). More than half of the lakes have areas of less than 10 hectares, while the largest is the Smradlivo Lake in the Rila range, at 212 hectares; the largest lake in the Pirins is Popovsko Lake, measuring some 112 hectares). Most of these lakes have a maximum depth of 2-5 m, while the deepest the Lake Okoto in the Rila range, at 37 m. The most famous lakes in the Rila Mountains are the Seven Rila Lakes, the Marichini Lakes, the Urdini Lakes, the Ribni Lakes, etc.; and the most famous ones in Pirin include the Vasilashki lakes, the Popovi lakes, the Vlahinski lakes, and the Banderishki lakes. The most important tectonic lakes are the Skalensko Lake (in the Stidovski section of the Eastern Balkan Mountains), the Kupensko lake (in the central region of the Balkan Mountains), Panichishte (in the Northern part of Rila Mountains) and Rabishko Lake, which has been dammed. The only relatively important lake among the coastal lakes and wetlands is Srebarna (a UNESCO natural heritage site). Typical landslide lakes are to be found along the Black Sea coast north of Varna and near the Aladzha Monastery. The Smolyan lakes are located in a vast landslip area north of the city, and consist of three larger and a few smaller lakes.
Medicinal mud deposits are located near the Shabla Tuzla, the Tuzlata, Varna Lake, Pomorie, Atanasovsko Lake, and the Mandra dam. There are turf deposits near the Batak dam in the Rhodopes, in the village of Baykalovo in the Konyavska Mountains), in the town of Straldzha, in the central region of the Tundzha River valley), near Varna Lake, and in the village of Sadovo, in the Gornotrakiyska lowlands). There are deposits of curative mud in the springs of Marikostinovo village in the Sandanski-Petrich valley; in the city of Banya in the Karlovo valley; in the canals at Ovcha Kupel in Sofia; in the cities of Velingrad and Asenovgrad; at Slivenski Bani, Starozagorski Bani, and Haskovski Bani; in the cities of Sapareva Banya, Blagoevgrad, Hisarya, Pavel Banya, Pomorie, and Primorsko; and at the resort complexes Albena and Sunny Beach; in the city of Burgas; and elsewhere.
The country’s favorable climate and natural attractions provide the basis for the development of its 142 resorts, of which 26 are marine resorts, 56 mountain resorts, and 58 are balneological resorts, not counting the numerous balneological and spa centers.
The soil diversity in the country is great. There are black soils, gray forest soils, maroon forest soils, vertisols, yellow soils, brown forest soils, mountain meadow soils, alluvial meadow soils, swamp soils, salty soils and humus carbonate soils. The territory of Bulgaria is divided into three regions with regard to is soils – northern Bulgaria, southern Bulgaria, and the mountainous zones.
Bulgaria is the second most biologically diverse nation in Europe. There are more than 12,360 plant species, 3,700 of which are higher species. Of these, 763 are included in the Red Book of Bulgaria, which lists rare or endangered species. About 750 plant types have been registered as medicinal, and 70% of these are economically valuable. The country exports about 15,000 tons of herbs each year. The forested areas amount to about four million hectares, which is 36.85% of the territory of the country. Of the deciduous broad-leaved forests, the most widespread are oak and beech. The oak forests are in areas up to an elevation of 1,000 meters, and the beech forests are mainly in the country’s central mountain ranges. Dense forests have developed at the lower reaches of the rivers Batova, Kamchiya, Ropotamo and Veleka. Natural coniferous forests are found in areas up to 2,200 meters above sea level, and are the most widely spread in the Rhodope Mountains. They mainly consist of spruce, fir and white pine. Black fir grows in the Slavyanka and Pirin Mountains, and white fir grows in the Central Balkans, the West Rhodope, the Middle Pirin, Rila, and Vitosha.
There are 27,000 species of invertebrate fauna in Bulgaria, and more than 750 species of vertebrates. Of these, 397 are birds, 207 are fresh-water and Black Sea fish, 94 are mammals, and 52 are amphibians and reptiles. Seven zoological regions are recognized throughout the country, four of which are in the Mediterranean climatic zone. Bulgaria is home to European, Euro-Siberian and Mediterranean flora and fauna, and the Mediterranean climate has strongly influenced the development of many species. The cave fauna in Bulgaria consists of more than 100 species. The Black Sea fish populations attract both sport and industrial fishing.
Three national parks have been established in the country: Pirin National Park (a UNESCO natural heritage site), Rila National Park, and the Central Balkans National Park. There are also 11 nature reserves – Belasitsa, Balgarka, Vratsa Balkan, Golden Sands, Persina, Rila Monastery, Rusenski Lom, Sinite Kamani, Strandzha and the Shumen Plateau.