Oka

Oka, an important navigable river of central Russia, the principal affluent of the Volga from the south, rises in the government of Orel, and flows in a generally north-east direction, and joins the Volga at the city of Nijni-Novgorod, after a course of 706 miles. Its basin comprises the richest and most fertile region of Russia. The principal towns on its banks are Orel, Bielew, Kaluga, Riazan, and Murom; the most important affluents are the rivers Moskwa, Kliasma, and Tzna. During spring the Oka is navigable from Orel to the Volga; but in summer the navigation is obstructed by sand-banks.