Lac, Lach, Lais, Lays
within that lake is a rock, and therein is a fair place as any on earth, and richly beseen.
Malory puts the Lake definitely in Britain, apparently somewhere near Caerleon. The Vulgate just as clearly puts the Lake in Benoye, France, and it is where the Damosel of the Lake raised Sir Lancelot from infancy. Hence, there must have been at least two magical Lakes, with one chief Lady of the Lake at a time in each.
Since the Lakes were magical and illusory (although the illusion was apparently quite tangible, even permitting the uninitiated to boat on the water’s surface), there is no need to search for real lakes with which to identify them.
It’s seen as an enchanted castle and it is from this castle Lancelot derived his surname ‘del Lac’.
Bois en Val | The Legend of King Arthur