Piva River (Piva) is the river in Bosnia and Herzegovina and Montenegro, shorter headwater of the Drina River, which it forms with the Tara River near the border with Bosnia and Herzegovina.
The Piva springs from the Sinjac Vrelo (Sinjac Spring), also called Vrelo Pive (Piva Spring) on Golija mountain, near the Monastery of Piva. Before the artificial Piva Lake was formed, the water from the well rushed into the Komarnica River thus creating the Piva River for the next 34 km.
Almost all of the both, the Piva and the Komarnica, course are flooded by the reservoir of the Piva Lake.
The canyon is cut between the mountains of Bioč and Pivska Planina on Montenegro side, and Maglić and Volujak from Bosnia and Herzegovina side, its 33 km long, deep up to 1.200 m and river generates immense power used for the power station of Mratinje (342 MW) which dammed the canyon in 1975. The dam is 228 m high, one of the highest in Europe and creates artificial Piva Lake, largest in Montenegro (12,5 km², altitude 675 m, 188 m deep).
After the dam, the Piva continues straight to the north, through the only remaining part of the canyon and enters Bosnia and Herzegovina some 2 km before finally meets the Tara River at Šćepan Polje, near the border with Montenegro, and with the Tara creates the Drina River.
The Piva belongs to the Black Sea drainage basin with its own drainage area of 1.270 km² and is not navigable.
Pivska Površ (Piva Plateau), is a high limestone plateau in the drainage area of Piva, between the mountains of Maglić, Lebršnik and Volujak on Bosnia and Herzegovina side, and Durmitor, Golija and Vojnik on Montenegro side. The plateau is 55 km long, 30 km wide with an average altitude of 1.200 m, the highest 2.159 m. The flow of the Piva (and Komarnica further into Montenegro) divides it in two regions: western one, Pivska Župa (Pivska Parish) and eastern one, Pivska Planina (Pivska Mountain). Area is characterized by many limestone features, like cavities deep pits called vrtača and excavations, and extremely sparsely populated (some 20 smaller settlements in Pivska Župa and 15 in Piva Mountain). Stock breeding is developed though, especially sheep.