The Volga Tributary is a major river in Russia that flows into the Caspian Sea. It has three main tributaries, the Oka, the Ola, and the Kama. The Oka is a river in central Russia that flows south and east into the Volga River. The Ola is a river in western Russia that flows north and east into the Volga River. The Kama is a river in the Ural Mountains that flows south and west into the Volga River. All three rivers are important sources of water for the Volga Tributary.