This book gave me chills. Song(she/they) completely sold me on the main character's devotion, navigating that fine line between truth and delusion. The horror reminded me a bit of Black Swan — there's even a sapphic side plot — though far more ambiguous in its ending. I have no background in competitive swimming, but despite my unfamiliarity I never found myself confused by the setting or plot. The descriptions of Ren Yu's interactions with water were perfect, especially for someone like me who's not overly fond of anything deeper than about four feet.

I was a bit confused about the intended audience of this book when I picked it up. As I read the early chapters it felt somewhat young to me, and I remember thinking it was the kind of book I would have loved when I was 14-15 but maybe it was only okay for me anymore. But it accelerates hard when it takes its dark turn, and ultimately I feel this is a book best appreciated by adults or older teens rather than the typical YA audience. The author includes a content warning in the front of the book, and she means it.

Despite the sapphic plot being very side, this nevertheless read to me as an incredibly queer book. Ren Yu's longing to become a mermaid, her certainty that she was and would be, felt very authentic to me while remaining distinct from issues of gender and sexuality. Some readers might find it troubling that the narrative doesn't wrap up with a clear bow, telling an unambiguous story of queer liberation. I personally didn't feel it was a problem; after all, the queer reading is only one possibility, albeit the one that feels correct to me personally.