- Category: Geographic Feature
- Type: Valley
- Latitude/Longitude: 51°44'2"N 3°50'29"W
- Eastings/Northings: 272925, 205530
- OS Grid: SN729055
- Mapcode Local: GBR H1.1VVV
- Mapcode Global: VH4JS.CPG2
Location and coordinates are for the approximate centre of Cwm Siôn within this administrative area.
Geographic features and populated places may cross administrative borders.