- Category: Water Feature
- Type: Island
- Latitude/Longitude: 52°0'28"N 5°4'50"W
- Eastings/Northings: 188666, 238869
- OS Grid: SM886388
- Mapcode Local: GBR CF.HNFM
- Mapcode Global: VH1QC.WSFM
Location and coordinates are for the approximate centre of Ynys Ddu within this administrative area.
Geographic features and populated places may cross administrative borders.