Llyn Ystumllyn, Gwynedd

• Parish/Community: Porthmadog
• Unitary Authority: Gwynedd
• Region: Wales

• Category: Water Feature
• Type: Other Water Feature

• Latitude/Longitude: 52°55'24"N 4°11'43"W
• Eastings/Northings: 252500, 338500
• OS Grid: SH525385
• Mapcode Local: GBR 5M.MTK7
• Mapcode Global: WH55K.JSC2

Location and coordinates are for the approximate centre of Llyn Ystumllyn within this administrative area. Geographic features and populated places may cross administrative borders.