One suggestion is that it is from "A-Ban" meaning "from the heights" due to its comparatively quick descent from hills to the sea.

[2] The Afan rises on the northern slopes of Mynydd Llangeinwyr to the east of Blaengwynfi, and flows in a generally south-westerly direction roughly parallel to the River Neath with which it shares its western watershed.

A motte and bailey castle stood on the banks of the river as it passed through Aberavon during the medieval period.

Its length is approximately 11 km, and its source lies above the village of Glyncorrwg, in the hills south of Glyn-neath.

Although the water is clear today, discharge from the many collieries along its lower reaches led to significant pollution.

The Pelenna, a major tributary that meets the Afan at Pontrhydyfen, suffered more severely from pollution than the main river because of the sulphur-rich coal that was produced by the mines in that area.

[3] At the height of coal extraction in the valley, there were several deep pits and numerous levels.

This pollution is now much mitigated[4] following extensive work promoted by the Environment Agency in the creation of engineered reed beds to treat the mine drainage.