The Avonbeg River is a tributary of the Avoca River in County Wicklow, originating in the Camenabologu Mountain within the Wicklow Mountains. It joins the Avonmore River at the "meeting of the waters" approximately 1.5 miles upstream of Avoca. While not considered a major fishery, the river is characterized as a spawning tributary and holds stocks of wild brown trout. The river can be heavily overgrown in places, which influences the angling approach.