The large river that flows into the Caspian Sea is the Volga River. Stretching approximately 3,530 kilometers (2,194 miles), it is the longest river in Europe and plays a crucial role in the region's ecology and economy. The Volga River basin supports agriculture, industry, and trade within Russia. It also serves as a significant transportation route, promoting shipping and tourism along its banks, enhancing the cultural and economic aspects of the surrounding areas.