Hans Christian Andersen's The Little Mermaid

Princess Marina lives in the undersea kingdom with her father, grandmother, and five older sisters. She is forbidden to go to the surface because she has not yet come of age. While exploring a ship destroyed by a storm, she discovers a statue of a human boy. She saves him and brings him to shore, leaving him there to be found. The prince and the princess are soon married. As the sun rises, Marina's body slowly turns to foam.