Nearest the trail is a large sinter lined basin, roughly elliptical in shape. A second vent, the pool vent, is located in the back wall of the trailside basin. These two vents both connect to a large hollow cavern in the back wall of the crater. Veteran's behavior appears chaotic at first. There is almost constant boiling, rumbling, and splashing from the main vent and the vent in the main basin.
Water continually spurts from the main and pool vents and there is constant evolution of steam.
The activity ebbs and builds. When Veteran is inactive, that is all that happens. When Veteran is active, it has major eruptions separated by periods of low intensity play and weak minor eruptions. Following a major eruption, Veteran stops all activity completely. Following the pause, activity gradually resumes, reaching a level of normal play, which eventually builds into an eruption, usually a weak minor eruption.