A common theme in the music of French composers at pre world war I was water. Debussy wrote En bateau (On the Boat), Sirenes (Sirens), Reflets dans l’eau (Reflections in the Water), Voiles (Sails), and La Cathedrale engloutie (The Engulfed Cathedral). Ravel wrote Jeux d’Eau (The Water Fountain), and Ondine.
So striking a peculiarity of modern music did these ‘water-pieces’ seem to one critic that he announced a lecture on La Musique aquatique. And then . . . Well, as the lecturer began to speak — he was an old man and obliged to hold his paper very near — he was annoyed by clicking and popping sounds. He decided to make a complaint and put down his paper. As he looked down from his dais he saw that each member of his high-spirited audience had put up his umbrella.
Source: Lockspeiser, Edward (1936) Debussy. London: J. M. Dent and Sons, p.121.