Cefn-coed-y-cymmer is a small community on the northwestern edge of Merthyr Tydfil County Borough in Wales. It is situated in the neck of land between the rivers Taf Fawr and Taf Fechan at their confluence. The village lies within the community of Vaynor. Immediately to the north of the village is the hill of Cefn Cil Sanws on the southern slopes of which is Merthyr Tydfil Golf Club. The village is bounded both to the north and the west by the Brecon Beacons National Park.

The Taff Trail is a walking and cycle path that runs for 55 miles (89 km) between Cardiff Bay and Brecon in Wales. It is so named because it follows the course of the River Taff. Along much of its length, it follows the National Cycle Network Route 8 that continues to Holyhead, and is substantially off-road.