This board-book version of the Hans Christian Andersen fairy tale is set in the Caribbean.Eliot's adaptation eliminates some of the more-disturbing plot elements in Andersen's original, making it feel much closer to the Disney version but with brown-skinned humans and merfolk. Once she's been given her feet, the Little Mermaid does not feel as though she's walking on glass and she is not motivated by a desire for an immortal soul, but the heroine still sacrifices her voice, her birth family, and her agency for the love of a rather clueless prince. The Caribbean setting is a good choice for a story in which the sea features prominently. Ortiz's lush illustrations reflect her Puerto Rican heritage. The sea witch, with her pointy nose, red lips, sharp-angled eyes, hoop earrings, and colorful headwrap is reminiscent of the vejigante masks that are part of carnival in Puerto Rico. However, the small trim size does a disservice to the art. The story has been simplified, but with four to seven lines of text per page, it is still too long for the board-book audience. As with other titles in the series, a larger, picture-book format would help this tale find a receptive audience of school-age children who are able to critique the subtext of the classic story even as they appreciate this version's gorgeous original art. Another format-audience mismatch for the Once Upon a World series. (Board book. 2-5)