The Olonka (Russian: Олонка) is a river in the Republic of Karelia, Russia. It gave the name to the town of Olonets by the river and eventually to the surrounding territory (Olonets Governorate, Olonets Krai, now Olonetsky District). It flows out of the reservoir and discharges into Lake Ladoga. It is 87 kilometres (54 mi) long, and has a drainage basin of 2,620 square kilometres (1,010 sq mi). Most important tributaries are (by Olonets) and rivers.