The Bala Lake Railway is a narrow-gauge railway along the southern shore of Bala Lake in Gwynedd, North Wales. The line, which is 4+1⁄2 miles (7.2 km) long, is built on a section of the former standard-gauge Ruabon–Barmouth GWR route that closed in 1965. Another section of the former permanent way is used by the Llangollen Railway. The Bala Lake Railway, which runs on 600 mm -gauge preserved rolling stock, is a member of the Great Little Trains of Wales.

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.