Llyn Goddionduon is a remote lake in the Gwydir Forest in north Wales.It lies at a height of 794 ft (242 m) and covers an area of 10 acres (40,000 m2). It is totally surrounded by coniferous forest, although a track leads up to it, enabling a water supply in the event of fire, and anglers also use this path. It is unusual in that it is totally natural, whereas nearly all of the other lakes in the forest have been partially or totally constructed as water sources for the mines which were scattered throughout the Forest. The lake is stocked with brown trout by the Betws-y-coed Anglers Club.