Aquamarine, by Alice Hoffman, 2001

Claire and Hailey spend the dog days of August at the decrepit Capri Beach Club, slated for dismantling at the end of the summer, just like their friendship, which will be torn apart when Claire's family moves in September. When a storm sweeps a torrent of ocean water, plants, and animals into the the Capri's swimming pool, Claire and Hailey are amazed to find it brings a mermaid with it. A flat, disappointing narrative that treats its characters as undifferentiated objects, always tells and never shows, and completely misses its opportunities for drama and emotional tension. Not recommended.