[2] It is named after Prince Idwal Foel, a grandson of Rhodri Mawr, one of the ancient Kings of Wales.

Legend states that the king's unfortunate offspring was murdered by being drowned in the lake.

In fact Idwal Foel died in battle against the Saxons in 942 and an alternate version claims that he was cremated beside the lake, as was the burial custom for Celtic nobility.

The lake is easily accessible on foot via a 900-metre long stone-paved path from Ogwen Cottage on the main A5 road.

There is a small pebble beach at the northwest edge of Llyn Idwal which is occasionally used by visitors for recreation, including bathing in the summer months.