Helig ap Glanawg was said to have lived here when his land was inundated by the sea, which formed the Lavan Sands which lie between the Great Orme's Head and the Menai Strait off the north coast of Gwynedd.
The legend states the remains of Llys Helig, said to be his palace but in fact the remnants of a glacial moraine,[2] can be seen at exceptionally low tides, this being near the Conwy channel, about a mile or so off the coast at Penmaenmawr.
These sons, according to various sources, were: Rachel Bromwich discusses what she refers to as the folk-tale of Cantre'r Gwaelod, another alleged sunken kingdom but in Cardiganshire.
Bromwich believes that the two stories influenced each other, and that "The widespread parallels to this inundation theme would suggest that the two stories are in fact one in origin, and were localized separately in Cardiganshire and in the Conway estuary, around two traditional figures of the sixth century.
[4] In the book New Directions In Celtic Studies Antone Minard wrote that "The Welsh legends of Cantre'r Gwaelod and Llys Helig (Helig's Court) contain the same details of audible bells beneath the waves and ruins which are visible at the equinoctial tides, which are the anchors of credulity in the story".