The edge of the Glowing Sea is an area located near the remains of the ruined freeway that marks the border between the relatively safe majority of the Commonwealth (from an environmental point of view) and the lethally irradiated hot zone, known as the Glowing Sea. A couple of raiders have holed up along the ruined freeway. Aside from this, the Edge consists only of long-dead trees and barren soil, serving as a grim warning to anyone foolish or desperate enough to venture into the Commonwealth's most hostile area.
Once the quest The Glowing Sea has been started, the Sole Survivor's search for Virgil, the fugitive Institute scientist who may have information on how to find and enter the Institute, begins here. If one is working with the Brotherhood of Steel, they will need to pass through here to reach the Sentinel site and search for the nuclear weapons for use as Liberty Prime's weaponry. Nearby Waypoint Echo will be manned with two Brotherhood soldiers, as well as Scribe Haylen.
The edge of the Glowing Sea only appears in Fallout 4.