- Category: Geographic Feature
- Type: Valley
- Latitude/Longitude: 51°49'1"N 3°7'21"W
- Eastings/Northings: 322712, 213748
- OS Grid: SO227137
- Mapcode Local: GBR F1.WN1W
- Mapcode Global: VH6CP.TLJG
Location and coordinates are for the approximate centre of Cwm Siôn Mathew within this administrative area.
Geographic features and populated places may cross administrative borders.