- Category: Water Feature
- Type: Island
- Latitude/Longitude: 52°46'53"N 4°44'44"W
- Eastings/Northings: 214915, 323956
- OS Grid: SH149239
- Mapcode Local: GBR GPNB.WF5
- Mapcode Global: WH33T.2CD1
Location and coordinates are for the approximate centre of Carreg Ddu within this administrative area.
Geographic features and populated places may cross administrative borders.