The Eventide River is a river that divides the city of Ravagog into two halves. One half is carved into a mountainside and the other is underground. The river is polluted, making it harder for a Hydrokinetic to manipulate. In Neverseen, Linh Song uses this river to make a tidal wave and flood part of Ravagog. The river gets filtered out before going out of Ravagog and running past the Wildwood colony. In Nightfall, it says that there are four river changes which are said to be quite jarring.
Lady Cadence's houseboat, Riverdrift, is on this river.
It was mentioned in Neverseen where Sophie and her friends were planning to go to Ravagog.
It is also mentioned in Nightfall when they go back to Ravagog with Lady Cadence.