Board Thread:General Discussion/@comment-6302057-20160307065615/@comment-6302057-20160331084638

Now the list is complete: I do wish that they had made the River of Lost Souls the Lethe as that's the logical choice considering the mythology.
 * Acheron (A.K.A. River of Lost Souls) - green (named in 5x14 and 5x16)
 * Styx - blue (shown in 5x14)
 * Cocytus - grey (shown in 5x14)
 * Lethe - yellow (shown in 5x15)
 * Phlegethon - lava