- Category: Water Feature
- Type: Island
- Latitude/Longitude: 53°23'39"N 4°34'20"W
- Eastings/Northings: 229056, 391707
- OS Grid: SH290917
- Mapcode Local: GBR HM2Q.QBK
- Mapcode Global: WH41X.QYW5
Location and coordinates are for the approximate centre of Ynys y Fydlyn within this administrative area.
Geographic features and populated places may cross administrative borders.