The Arpa (Armenian: Արփա; Azerbaijani: Arpaçay) is a river that flows through Armenia and Azerbaijan. Originating in Armenia's Vayots Dzor province (marz), it is a left tributary of the Aras. It is 128 km (80 mi) long, and has a drainage basin of 2,630 km (1,020 sq mi). It runs through many cities and towns, including Jermuk, Vayk, Yeghegnadzor, Areni, and then reaches Azerbaijan's Nakhchivan exclave, flowing through Oğlanqala, Siyaqut and Qışlaqabbas.

• List of lakes of Armenia
• Geography of Armenia