- Category: Water Feature
- Type: Inland Water
- Latitude/Longitude: 52°50'53"N 3°45'45"W
- Eastings/Northings: 281398, 329300
- OS Grid: SH813293
- Mapcode Local: GBR 65.SQHL
- Mapcode Global: WH679.5NKY
Location and coordinates are for the approximate centre of Llyn Grych-y-waun within this administrative area.
Geographic features and populated places may cross administrative borders.