Debussy's "La Cathédrale engloutie" (Sunken Cathedral) from Preludes, Book 1 (1910) is based on an ancient Breton myth in which a cathedral, submerged underwater off the coast of the Island of Ys, rises up from the sea on clear mornings when the water is transparent. Sounds can be heard of priests chanting, bells chiming, and the organ playing, from across the sea.
