She's in Love (2000)

Based partially on the Little Mermaid, a rich, fifteen year old girl with a flair for swimming rebels when her father is about to marry a woman that can only be described as "the evil sea witch". In order to see a new boyfriend that no one approves of, she makes a deal with her future step-mother. As all her problems begin to drown her, she must make choices about her dreams and family.