- Category: Geographic Feature
- Type: Hill or Mountain
- Latitude/Longitude: 52°59'40"N 4°23'1"W
- Eastings/Northings: 240113, 346784
- OS Grid: SH401467
- Mapcode Local: GBR 5C.H9LL
- Mapcode Global: WH43Y.MZQQ
Location and coordinates are for the approximate centre of Gyrn Ddu within this administrative area.
Geographic features and populated places may cross administrative borders.