Struma

The Struma or Strymonas (Bulgarian: Струма, romanized: Struma, pronounced [ˈstrumɐ]; Greek: Στρυμόνας, romanized: Strymónas, pronounced [striˈmonas]) is a river in Bulgaria and Greece. Its ancient name was Strymon (Greek: Στρυμών, romanized: Strymṓn, pronounced [stryˈmɔːn]). Its drainage area is 17,330 km (6,690 sq mi), of which 8,670 km (3,350 sq mi) in Bulgaria, 6,295 km (2,431 sq mi) in Greece and the remaining 2,365 km (913 sq mi) in North Macedonia and Serbia. It takes its source from the Vitosha Mountain in Bulgaria, runs first westward, then southward, forming a number of gorges, enters Greece near the village of Promachonas in eastern Macedonia. In Greece it is the main waterway feeding and exiting from Lake Kerkini, a significant centre for migratory wildfowl. Also in Greece, the river entirely flows in the Serres regional unit into the Strymonian Gulf in Aegean Sea, near Amphipolis. The river's length is 415 kilometres (258 miles) (of which 290 kilometres (180 mi) in Bulgaria, making it the country's fifth-longest and one of the longest rivers that run solely in the interior of the Balkans.

Parts of the river valley belong to a Bulgarian coal-producing area, more significant in the past than nowadays; the southern part of the Bulgarian section is an important wine region. The Greek portion is a valley which is dominant in agriculture, being Greece's fourth-biggest valley. The tributaries include the Konska River, the Dragovishtitsa, the Rilska River, the Blagoevgradska Bistritsa, the Sandanska Bistritsa, the Strumitsa, the Pirinska Bistritsa and the Angitis.