Underworld

The underworld is found below the surface of Ebdypha but above the Old Sea. The upper portions of the underworld contain underchannels and vast cave systems, while the true underworld lit by the Undersun is yet to be seen by a reliable source.
Some of the ancient Arizathrans discovered extensive underground rivers in the underworld that flowed with waters of the Old Sea. They called them Underchannels and found that they allowed one to ride the currents to other continents, and they built their own empire called Murut.
The Ifredans have the technology and geography to deep-mine quite close to the underworld where they extract Visite, but they are yet to locate the true underworld itself.