LLYN-OGWEN, a lake in Carnarvon; near the head of the river Ogwen, between Carnedd-Davydd and Glyder-Fawr, 5 miles S by E of Bethesda. It is nearly a mile long; and it abounds with fine trout. The Ogwen river, immediately on leaving it, traverses a wild gorge, called Benglog pass, and makes a series of falls of aggregately more than 100 feet.

(John Marius Wilson, Imperial Gazetteer of England and Wales (1870-72))