Merthyr Mawr is a broad dune system west of Porthcawl, among the largest in Europe. Its shifting ridges and hollows are good for a long sandy walk, wildlife spotting, and views back toward the coast.
The dunes also have a film footnote: scenes for Lawrence of Arabia were shot here. There is usually a charge for the car park, but once you are out among the dunes the place feels surprisingly wild.