The Edgeworld is the name given to the world that the Edge Chronicles is set in.
The entire Edgeworld was situated on the edge of a colossal cliff. Most of the world was taken up by the Deepwoods, a vast and wild forest. To the north and south of the Deepwoods were the Edgelands, empty and desolate lands said to be inhabited by spirits. West of the Deepwoods were the Thorn Forests, the Nightwoods, and Riverrise. To the west of Riverrise were several mountains, uninhabited except for a few extremely primitive life forms such as Nameless Ones. What lay beyond these mountains is unknown.
East of the Deepwoods were the Twilight Woods, the Mire, the twin cities of Undertown and Sanctaphrax, and the Stone Gardens. The long and winding Edgewater River stretched out across the entirety of the known world, having its source in Riverrise, and its end at the Edge's tip, where it culminated in an enormous waterfall.
Beyond the Edge
The sky above the Edge was classified into Low Sky, Middle Sky, and High Sky. The sky beyond the Edge was known as Open Sky, and was practically uncharted. Open Sky was believed to extend indefinitely.
What lay at the base of the Edge is unknown - indeed, for many millennia it was believed the Edge Cliff had no base at all, and simply existed above an endless abyss.. At the end of the Immortals, Nate Quarter and Ambris Hentadile were shown descending the cliff into the darkness below, and the novel's final illustration showed the Edge Cliff rising up out of a flat plain - seemingly proving that there is solid ground below the Edge.
No canon material has ever been revealed for what lies west of the Edge, beyond Riverrise and the Nightwoods.