The Drina (Serbian Cyrillic: Дрина, pronounced [drǐːna]) is a 346 km (215 mi) long river in the Balkans, which forms a large portion of the border between Bosnia and Herzegovina and Serbia. It is the longest tributary of the Sava River and the longest karst river in the Dinaric Alps which belongs to the Danube River drainage basin.
The Drina originates from the confluence of the rivers Tara and Piva, in the glen between the slopes of the Maglić, Hum and Pivska Planina mountains, between the villages of Šćepan Polje, Montenegro and Hum, Bosnia and Herzegovina.