Situated on the northeastern flank of Plinth Peak, the Bridge River Vent has an elevation of . It has oversteepened walls covered with ice and debris from volcanic activity and slope collapses. The crater is roughly bowl-shaped, although it is breached on the northern side. Because the Bridge River Vent is located on the northern slope of the Mount Meager massif, it represents a satellite vent. The eruption that formed the Bridge River Vent was probably fed through a conduit from the magma chamber below the massif. A stress field controlled by regional tectonics has been commonly invoked to explain the dynamics of lateral flow (flowing laterally rather than vertically toward the surface) of magma from a reservoir to produce such eruptions.