The Vorotan (Armenian: Որոտան), or Bargushad (Armenian: Բարգուշատ, Azerbaijani: Bərgüşad) or Bazarchay (Azerbaijani: Bazarçay), is a river in the South Caucasus that is the largest right tributary of the Hakari river. It starts from the northwestern slopes of the Syunik Plateau, from the Tsalk pond and adjacent springs at an altitude of 3,045 m, receives the water of streams flowing from several small ponds, as well as the springs of Gorayk village, then it flows in a southeastern direction through the territory of Sisian and Goris regions. It flows through Armenia for 119 kilometres (74 mi) in a generally south-easterly direction. The river enters Azerbaijan again, flowing for 43 km (27 mi) through the districts of Qubadli and Zangilan. The lower section of the Hakari, from its confluence with the Vorotan until its confluence with the Aras river, is sometimes considered to be part of the Vorotan.

The river flows mostly through mountainous regions of Armenia and in several places has formed deep canyons. The towns of Sisian and Qubadli lie along its course. Six kilometers from Sisian, the river forms a waterfall — the "Shaki Waterfall" (Armenian: Շաքիի ջրվեժ) — that is 18m high. The river forms a natural monument – the "Devil's Bridge" — near Tatev Monastery. There are mineral pools at the base of the travertine arch.

During the Soviet period, three reservoirs forming the Vorotan Cascade were constructed. They supply Armenia with hydro-electric power and water for irrigation. To increase the volume of water in Lake Sevan, a 21.6-kilometre (13.4 mi) tunnel was constructed to abstract some of the Vorotan's waters and divert them to the lake.

Begun during the 1980s, work was stopped in 1988, when only 18 km (11 mi) had been completed, because of the outbreak of the First Nagorno-Karabakh War. The Armenian government finally completed the Vorotan tunnel in 2003. Prior to this, a second tunnel — "Arpa–Sevan" — was completed in 1981. This diverts some water from the Arpa River for Lake Sevan. The waters coming through the two tunnels have resulted in the lake's water level rising. In 2007 it was reported that the water level had risen by 2.44 metres (8.0 ft) in the previous six years.

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  Shaki Waterfall
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  Vorotan River Canyon near Tatev
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  The "Devil's Bridge" natural arch near Tatev Monastery
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  The base of the "Devil's Bridge" 1 km from Goris
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  The Vorotan flowing through Qubadli District