- Category: Water Feature
- Type: Island
- Latitude/Longitude: 52°47'5"N 4°41'52"W
- Eastings/Northings: 218149, 324237
- OS Grid: SH181242
- Mapcode Local: GBR GPSB.DSY
- Mapcode Global: WH33T.T819
Location and coordinates are for the approximate centre of Ynys Gwylan-bâch within this administrative area.
Geographic features and populated places may cross administrative borders.