- Category: Geographic Feature
- Type: Valley
- Latitude/Longitude: 51°50'56"N 3°10'30"W
- Eastings/Northings: 319149, 217371
- OS Grid: SO191173
- Mapcode Local: GBR YZ.TM1Q
- Mapcode Global: VH6CG.XS8C
Location and coordinates are for the approximate centre of Cwm Onnau within this administrative area.
Geographic features and populated places may cross administrative borders.