Board Thread:General Discussion/@comment-6302057-20160307065615/@comment-6302057-20160307112842

Rwo wrote: I only see FIVE rivers. Gray, Blue, Yellow, Red, and Green. My bad, I was going on the traditional Greek mythology. There are in fact only five seen in the episode.

I believe that it would be the river Acheron that forms the portal to the Underworld (the one ferried by Charon), with the other five appearing in Hades' lair. Acheron is also described as a primary river of the Underworld with the Styx and the Cocytus flowing from it, so it makes sense that Acheron is the portal river with the ferry with the rest in Hades' lair.