Slightly unrelatedly, the last time I reread Faces Under Water I noticed that not only is it in dialogue with The Merchant of Venice, but the plot is an inverted Tempest, with our protagonist as Ferdinand and the girl as Miranda and her father as the evil-est Prospero ever, which makes Shaachen the King of Naples-- an idea which, oddly enough, works for me. But yeah, the drowning/not-drowning, and the conspiracy behind it, and the trials to win the girl imposed by the father, and it makes the masks Ariel which is nifty, and the magpie probably Caliban which is niftier. But the thing that made me decide it was intentional is that it explains Calypso's name, which nothing previously had done to my satisfaction. That is a really good book.