The healing power of mineral springs has been recognized since the time of the Thracians, who were renowned as healers. “The Holy Springs of Thrace” were famous throughout the Roman Empire. Few countries in Europe can rival Bulgaria’s spa, balneological and wellness tourism, with its abundance and diversity of thermal mineral waters and curative mud deposits. There are more than 550 known sources with 1,600 springs that have a total capacity of 4,900 per second. Predominant are waters with low mineral content – 66.7% of the springs, as opposed to 14.4% with higher mineral content and 17.9% that are naturally carbonated. Cool mineral springs are found throughout the country – Narechen (Asenovgrad region), Shipkovo (Troyan region), Ovcha Kupel (Sofia), Smochan, (Lovech region), Voneshta Voda (Gabrovo region), Merichleri (Simeonovgrad region), and elsewhere. The spring with the highest temperature is Sapareva Banya (103ºС), also the only geyser in Bulgaria and Continental Europe. The most famous thermal springs in the Balkan Mountains are in the regions of Varshets, Barziya, Lakatnik, Opletnya; on the Sofia plain – Bankya, Gorna Banya, Knyazhevo, Ovcha Kupel, Sofia, Pancharevo; in the Srednogorie – Strelcha (40°С), Hisarya (49.5°С), Banya (51.1°С), Pavel Banya (54.6°С), Starozagorski Bani (45.8°С); along the valley of Struma River – Blagoevgrad, Simitli, Sandanski, Levunovo and Marikostinovo; along the valley of Mesta River – Banya (56оС), Dobrinishte (43°С) and the village of Eleshnitsa (56°С); in the Rhodope Mountains – Devin, Velingrad, Banite.
Most widespread in Bulgaria are the nitrogen thermal waters, found in the springs around Sapareva Banua, Simitli, Narechen, Momin Prohod, and elsewhere. Carbon acid is contained in the waters of the springs near Mihalkovo, Slivenski Mineralni Bani, Stefan Karadzhovo; hydrogen sulphide is contained in the thermal waters in the Sofia lowlands. Half of the thermal waters contain increased radioactivity, showing levels higher than 15 eman/l, such as the Klisura spring (200 eman/l) and the Strelcha spring (250 eman/l), among others. Particularly high radioactivity has been registered in the springs of Momina Banya (560 eman/l) and the Narechen springs (1,300 eman/l).
