The River Erinin is one of the major rivers of the Westlands. It rises in the Spine of the World and flows westwards to form the southern borders of both Shienar and Arafel. In Shienar the river is about four days ride south of Fal Dara. It is only about sixty paces wide there, with a small village built on its banks and a ferry for crossing.
It flows south from Arafel and is joined by the River Antaeo. It continues southwards until it reaches the island and city of Tar Valon, where it splits in two, with the western branch named the Alindrelle Erinin and the eastern branch named the Osendrelle Erinin. The river reforms south of the island and continues to flow south, where it forms the western border of Cairhien and the eastern border of Andor. The river flows between the Andoran port town of Aringill and the Cairhienin village of Maerone. The River Luan also flows into the Erinin shortly after it meets the Cairhienin border.
South of Cairhien, the river is joined by another major tributary, the River Iralell, before it reaches the borders of Tear. Just south of the capital, the river breaks up in a maze-like delta called the Fingers of the Dragon before finally reaching the Sea of Storms.