The Vorilon River is the longest river in Lanad i'Sarois, with its headwaters in the western Onyl Mountains in Tanilon. From there, it takes a mostly southerly course through the MidLands before bending westwards along the southern border of Faxanadu. Its mouth is located near the city of Eolis, where it empties into the Living Ocean.
The Vorilon forms an important trade route through the central Lanad. Through Alior and Lan-Zarek it parallels the Old Gnome Road, and there are several towns along this stretch that serve the various communities of Halflings, lizard men, saurials, and others that make their homes along its course. It is also the primary point of contact with the Karis of Faxanadu, and over the centuries boats carrying mercenaries upriver have been a common sight, especially during the Wars of Arin.
In past times, the Vorilon was also called the Onyx River, but since the fall of the Onyx Empire, of which it was the main water source, it has been renamed.