Lyonesse is a country in Arthurian legend, particularly in the story of Tristan and Iseult. Said to border Cornwall, it is most notable as the home of the hero Tristan, whose father was king. In later traditions Lyonesse is said to have sunk beneath the waves some time after the Tristan stories take place, making it similar to Ys and other lost lands in medieval Celtic tales, and perhaps connecting it with the Isles of Scilly. In medieval Arthurian legend, there are no references to the sinking of Lyonesse, for the simple reason that the name originally referred to a still-existing place. Lyonesse is an English alteration of French Léoneis or Léonois (earlier Loönois), a development of Lodonesia, the Latin name for Lothian in Scotland. Continental writers of Arthurian romances were often puzzled by the internal geography of Great Britain; thus it is that the author French Prose Tristan appears to place Léonois contiguous, by land, to Cornwall. In English adaptations of the French tales, Léonois, now "Lyonesse", becomes a kingdom wholly distinct from Lothian, and closely associated with the Cornish region, though its exact geographical location remained unspecified. The name was not attached to Cornish legends of lost coastal lands until the reign of Elizabeth I of England, however. However, the legendary lost land between Land's End and Scilly has a distinct Cornish name: Lethowsow. This derives from the Cornish name for the Seven Stones reef, on the reputed site of the lost land's capital and the site of the notorious wreck of the Torrey Canyon. The name translates into English as "the milky ones", from the constant white water surrounding the reef.
ANALOGUES IN CELTIC MYTHOLOGY
The legend of a sunken kingdom appears in both Cornish and Breton mythology. In Christian times it came to be viewed as a sort of Cornish Sodom and Gomorrah, an example of divine wrath provoked by unvirtuous living, although the parallels were limited in that Lyonesse remained in Cornish thought very much a mystical and mythical land, comparable to the role of Tir na nÓg in Irish mythology. There is a Breton parallel in the tale of the Cité d'Ys, similarly drowned as a result of its debauchery with a single virtuous survivor escaping on a horse, in this case King Gradlon. The Welsh equivalent to Lyonesse and Ker Ys is Cantre'r Gwaelod, a legendary drowned kingdom in Cardigan Bay. It is often suggested that the tale of Lyonesse represents an extraordinary survival of folk memory of the flooding of the Isles of Scilly and Mount's Bay near Penzance. For example, the Cornish name of St Michael's Mount is Karrek Loos y'n Koos - literally, "the grey rock in the wood". Cornish people around Penzance still get occasional glimpses at extreme low water of a sunken forest in Mount's Bay, where petrified tree stumps become visible. The importance of the maintenance of this memory can be seen in that it came to be associated with the legendary British hero Arthur, although the date of its inundation is actually c.2500 BC.
