The Arpa (Armenian: Արփա; Azerbaijani: Arpaçay) is a river that flows through Armenia and Azerbaijan's Nakhchivan exclave. 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, Oğlanqala, Siyaqut and Qışlaqabbas.

• List of lakes of Armenia
• Geography of Armenia