The geography of the lower Afan Valley is delineated primarily by the surrounding mountains, with Y Foel dominating the west side of the lower valley, and Mynydd Dinas to the east, and by Afon Afan (the River Afan) that flows along its length.

The upper Afan Valley is a narrow valley with heavily wooded steep sides, dotted with a number of villages that were home to coal miners and their families.