I'm not a lust-ridden 'tween-age girl, but if I were and a mermaid happened to find her way into my swimming pool, the last thing I'd do is take her shopping and let her steal the boy of my dreams. But I'm catty and shallow. The two best friends in ''Aquamarine" are sweet and fair. So when the bubbly Aquamarine (Sara Paxton) winds up in a Florida beach town after a storm, Claire (Emma Roberts, who's Eric's daughter and Julia's niece) and Hailey (the pop singer known as JoJo) try to give her what she wants. Love. Of course, at sundown Aqua's legs turn back into a tail, which means she doesn't have much time to find it.
According to Aqua, her father plans to marry her off to a merman she doesn't love. Dad doesn't believe love exists. She insists it does, and daddy gives her three days to prove it. The boy she picks is Raymond (Jake McDorman), the same permanently shirtless lifeguard Hailey and Claire have been wanting all summer. But if they help a mermaid, they get a wish, and since Hailey is about to move to Australia, they enlist in Project Love and plan to use their wish to stay together.
If I were these two I'd be wishing for filmmaking better than the ABC Family Channel stuff they've got. But 12-year-old girls won't care that some of the overdubbed dialogue in ''Aquamarine" makes it seem like a lesser work of Italian neorealism. (The ones who do should write me. I might know some 13-year-old nerds who'd love to watch ''Open City" with you.)
Most girls will just be pleased that Alice Hoffman's book has been faithfully adapted, that Roberts has inherited the family's good dental work, that Paxton is like Reese Witherspoon with a tail, and that JoJo is playing someone other than the underage vixen she does in her PG music videos. The town vamp is Cecilia (Arielle Kebbel), the dangerously tan, Mandy Moore-monster who is also in pursuit of Raymond. (He's the only boy in town worth wanting.) Girls will hate her, but if the intended audience is anything like Claire and Hailey, they will come to feel sorry for her, too.
''Aquamarine" is part ''Splash" and part ''Clueless" (when that dressing-room montage comes hurtling toward you, duck). But girls will know ''Aquamarine" is unique because it's the rare movie that fiercely respects the altruistic loyalty that bonds girls to one another. Cute boys Hasselhoffing in slow motion on the sand come and go, but a best friend is forever.
Wesley Morris can be reached at firstname.lastname@example.org.