- Category: Water Feature
- Type: Inland Water
- Latitude/Longitude: 53°23'41"N 4°34'5"W
- Eastings/Northings: 229335, 391731
- OS Grid: SH293917
- Mapcode Local: GBR HM3Q.L85
- Mapcode Global: WH41X.SXWV
Location and coordinates are for the approximate centre of Llyn y Fydlyn within this administrative area.
Geographic features and populated places may cross administrative borders.