The local authority area stretches from the coast to the borders of the Brecon Beacons National Park. The majority of land is upland or semi-upland in character, and 43% is covered by forestry with major conifer plantations in upland areas. Most of the lower lying flat land is near the coast around Port Talbot.
An extensive dune system stretches along much of the coast, broken by river mouths and areas of development. The upland areas are cut by five valleys: Vale of Neath, Dulais Valley, Afan Valley, Swansea Valley, Upper Amman Valley.