Related Clues:

• Unpleasant place to cross
• River surrounding Hades
• Corrupt place by underworld river
• Hellish flower, reportedly bonebreaker
• River gets bogged down, so to speak
• River of the underworld
• The last river one crosses in remote rural areas, say?
• Not a nice location to cross
• Reach no dreadful, infernal river
• Moon of Pluto
• One of the underworld rivers and small branches, say
• Mythological underworld boundary river
• Olympians swore oaths on it
• Underworld river in Greek mythology
• The way you start to cross the river