Off the coast of Dinas Dinlle in Gwynedd lies a rocky reef exposed at low tide and known in Welsh folk tradition as Caer Arianrhod, said locally to be the remains of a drowned court that once belonged to the figure of the Mabinogi, submerged beneath the waves like other legendary sunken lands of Welsh lore. The identification of a real tidal feature with the tale's heroine is a matter of local folklore and place-name tradition recorded by antiquarians rather than anything stated in the medieval text itself, which locates her within the narrative world of the Fourth Branch rather than any specific coastal geography.
Arianrhod's modern reputation as a lunar or star goddess owes a great deal to twentieth century writers, most influentially Robert Graves, whose 1948 study The White Goddess wove her name, her silver wheel, and her associated constellation into a wide ranging and highly speculative synthesis of a supposed pan-European moon goddess, an interpretation embraced enthusiastically within later Wiccan and Goddess-movement practice but treated with considerable skepticism by specialists in medieval Welsh literature, who read her primarily as a proud, wronged noblewoman within a dynastic tale rather than a survival of an ancient sky cult. The gap between the careful, text-based reading of the Mabinogi and the freer modern reimagining is itself instructive: Arianrhod has, in effect, two afterlives, one as a literary character preserved in medieval manuscript, the other as a contemporary goddess archetype largely built in the last hundred years.