- Category: Water Feature
- Type: Inland Water
- Latitude/Longitude: 52°57'34"N 3°54'50"W
- Eastings/Northings: 271527, 341949
- OS Grid: SH715419
- Mapcode Local: GBR 5Z.KPNW
- Mapcode Global: WH55H.VWB1
Location and coordinates are for the approximate centre of Llyn y Cefn within this administrative area.
Geographic features and populated places may cross administrative borders.