Bala Lake is a large freshwater glacial lake in Gwynedd, Wales. The River Dee, which has its source on the slopes of Dduallt in the mountains of Snowdonia, feeds the 3.7 miles (6.0 km) long by 0.5 miles (0.8 km) wide lake. It was the largest natural body of water in Wales even before its level was raised by Thomas Telford to provide water for the Ellesmere Canal.

Gwynedd is a county in the north-west of Wales. It borders Anglesey across the Menai Strait to the north, Conwy, Denbighshire, and Powys to the east, Ceredigion over the Dyfi estuary to the south, and the Irish Sea to the west. The city of Bangor is the largest settlement, and the administrative centre is Caernarfon. The preserved county of Gwynedd, which is used for ceremonial purposes, includes the Isle of Anglesey.