Llyn Ogwen is a lake in north-west Wales. It lies alongside the A5 road between two mountain ranges of Snowdonia, the Carneddau and the Glyderau.
Llyn Ogwen lies at a height of about 310 metres above sea level and has an area of 78 acres, but is a very shallow lake, with a maximum depth of only a little over 3 metres. It is fed by a number of streams from the slopes of the mountains which surround it, which include Tryfan and Pen yr Ole Wen.
The lake is popular with anglers and is said to contain excellent trout.