51°28′48″N 03°38′33″W / 51.48000°N 3.64250°W
Merthyr Mawr Sand Dunes are sand dunes and a Site of Special Scientific Interest in Bridgend, south Wales. The village of Merthyr Mawr is nearby.
The largest dune at the site is known as The Big Dipper and is the second-largest of its kind in Europe, measuring around 200 feet (61 m).