Bala Lake (Llyn Tegid in Welsh), in Gwynedd, was the largest natural body of water in Wales prior to the level being raised by Thomas Telford to help support the flow of the Ellesmere Canal.
It is 4 miles / 6.4 km long by a mile / 1.6 km wide and is crossed by the River Dee and its waters are famously deep and clear. The town of Bala sits at its northern end and the narrow gauge Bala Lake Railway runs for several kilometres along the lake's southern shore.
Bala Lake has abundant Pike, European perch, trout, eel and Gwyniad. It also contains the very rare mollusc Myxas glutinosa - the Glutinous snail. According to legend the lake is inhabited by a monster known affectionately as Teggie.
Also according to legend, while the Dee itself flows into the lake, the waters never mix.
The lake now forms part of the River Dee regulation System and the level at its outflow is automatically controlled. Depending on flow conditions and the level of water in Llyn Celyn, water can flow either into the lake or out from the lake at the normal outflow point.
A number of local companies provide kayaks, yachts and various other types of boats for rent to tourists. On holidays these services get very busy and forward booking is essential.