- Category: Water Feature
- Type: Island
- Latitude/Longitude: 52°8'22"N 4°36'42"W
- Eastings/Northings: 221359, 252238
- OS Grid: SN213522
- Mapcode Local: GBR D1.7BQV
- Mapcode Global: VH2MJ.0HQ6
Location and coordinates are for the approximate centre of Carreg Sioni within this administrative area.
Geographic features and populated places may cross administrative borders.