This chapter focuses on the four major rivers that flow into the eastern Baltic Sea. From west to east, these are the Vistula, the Nemunas, the Western Dvina, and the Narva. Other larger rivers in this region are the Pregolja, the Venta, the Lielupe, the Gauja, the Parnu, and the Luga. All these rivers are meandering, lowland rivers fringed by vast floodplains. They drain the eastern continental plains and Baltic area. This area includes eastern Poland, Lithuania, Latvia, Estonia, and western and central Belarus; the Kaliningrad and Pskov regions as well as the western Leningrad region in Russia. The area belongs to the Central European mixed forest and North Atlantic moist mixed forest biomes. It is bordered by the Carpathian montane coniferous forests in the southwest and Scandinavian and Russian taiga in the east. All these rivers are regulated to some extent, modifying flow regimes, and suppressing the migration of fishes. The Upper Vistula has been converted into a chain of dams and the Włocławek reservoir intersects the lower river. In the middle Nemunas, the Kaunas hydroelectric power station was built. Three major hydropower stations occur along the Western Dvina and a large hydroelectric power plant is near the mouth of the Narva River.