|Mouth||Bay of Suvol|
|Length||[convert: needs a number]|
|Basin size||[convert: needs a number]|
|• maximum||[convert: needs a number]|
|• average||[convert: needs a number]|
The Er River is a north-flowing river in eastern Aurora that serves as the primary waterway for the nation of Baykalia. At an approximate distance of , the Er river basin covers land in Baykalia, Oscrelia, and Caltharus. The Er river serves as a major water source and a major avenue for trade for Baykalia, as is provides an easily accessible avenue for resource extraction from the Kalivian Mountains.
The river has two major tributaries, two of which are located within the Kalivian Mountains; the western called Tetrier and the eastern called Lurjier. The western source is considered the headwaters as the longest distance away from the delta, but the eastern source provides the largest amount of water. The two tributaries converge at the Baykalian city of Irkula. Further downstream, the river approaches Chita and discharges into the Bay of Suvol.