It begins high on the slopes of Aran Benllyn about five miles south of Lanuwchllyn and flows south - west into the River Mawddach near Cymer Abbey .
The River Wnion is a river in the southeast of Gwynedd , Wales .
River Wnion begins high on the slopes of Aran Benllyn about five miles south of Lanuwchllyn and flows south - west into the River Mawddach near Cymer Abbey .
The River Wnion is a river in the southeast of Gwynedd , Wales .