"Aquamarine" walks (or, in this case, swims) proudly from frame one toward exactly what it is: a tween-targeted version of the 1989 animated classic, "The Little Mermaid," and 1984's more adult-oriented "Splash." Directed with good will to spare and a lot of colorful backdrops by first-time filmmaker Elizabeth Allen, the film hits all of the postmarks of the girl-power genre—the hunky dream guy, the vapid adversary out to snatch him for herself, the big dance, the bubblegum pop soundtrack, and the trying-on-clothes montage. Even as these predictable conventions splash about, though, "Aquamarine" unveils itself to be fairly shrewd in its PG-rated depiction of coming of age, and eventually about more universal topics than its fantasy-laden mermaid plot suggests upon first glance. In other words, the film refuses to talk down to its audience.

With the summer quickly drawing to a close in their Florida beach town, 13-year-old best friends Claire (Emma Roberts) and Hailey (Joanna 'JoJo' Levesque) are struggling to deal with Hailey's impending move with her marine biologist mother to Australia. When a big storm washes ashore one night, the girls stumble upon something the next morning that they can't quite believe: a mermaid named Aquamarine (Sara Paxton) hiding out in a resort swimming pool.

As Aqua befriends the girls and experiences having legs, which she grows during the daytime when out of water, for the first time in her life, her purpose comes into focus: she has persuaded her father to hold off her arranged engagement for a chance to come to land and prove that there is such a thing as true love in the world. With only three days to find it, Claire and Hailey help Aqua as she sets out to make Raymond (Jake McDorman), the hottest guy on the beach, fall in love with her. When the stuck-up Cecilia (Arielle Kebbel) discovers Aqua's true identity, however, it may just ruin any chance she might have with Raymond.

Adapted by screenwriters Jessica Bendinger (2004's "First Daughter") and John Quaintance from the young adult novel by Alice Hoffman, "Aquamarine" is an entertaining, endearingly performed fantasy-comedy that does quite well at working over some of its rougher patches. The aforementioned music montages—there's not only one set at the mall, but another in which the three girls study teen magazines to learn how to act around guys—are overproduced to the point that they look like music video parodies, while the occasionally iffy visual effects give away a limited budget. As for the villain of the piece, Cecilia, every time it looks as if a refreshing attempt is being made to deepen her beyond one dimension, the film pulls back and caricaturizes her. At least the tried-and-true role is memorably played by Arielle Kebbel (2005's "Dirty Deeds"), a talented rising actress who happens to be a dead ringer for Mandy Moore, who, in turn, had a very similar part in 2001's "The Princess Diaries."

Despite all of those shortcomings and nitpicks, "Aquamarine" proves to be nearly irresistible just from a sheer congenial standpoint. The comedy, which moves between witty dialogue and broader physical strokes, never comes off as forced, while the emotional subplots involving everything from the untimely deaths of Claire's parents, to Claire's fear of water, to Hailey's deadbeat father, to Aqua's earnest search for what she believes to be true love, are unusually soulful and even touching. Perhaps the movie's strongest relationship, and the most convincing, is the tight friendship between Claire and Hailey, who can't bear to envision their lives without each other but gradually come to understand that's the way it has to be.

The young leads are fresh finds, each one ideally cast. Emma Roberts (2001's "Blow") and singing sensation Joanna 'JoJo' Levesque (making her acting debut) are unaffected joys to watch onscreen as Claire and Hailey, free of most of the forehead scrunches, hair tosses and cutesy mugging for the camera that plagues a lot of performers in their age group. They handle their dramatic moments with the same believable assuredness as their lighter scenes, and appear all the more comfortable because their characters have been written to be close approximations of what giggly, boy-crazy 13-year-old girls are really like as they struggle to find themselves and fit in with their peers.

As the title character, Sara Paxton (2004's "Sleepover") is delightful, bringing to life the sort of adorably naive and plainly lovable heroine that the viewer wants to root for. It probably isn't a coincidence that Aquamarine is unmistakably reminiscent of Arielle from "The Little Mermaid," either. Kudos, also, to Jake McDorman (TV's "Quintuplets") for making Raymond into more than a bland object of affection. McDorman's role is relatively thankless, to be sure, but he handles it well enough that it doesn't feel like a boring cliché.

For 105 minutes, "Aquamarine" totters eloquently between cotton-candy frothiness and more serious subject matter, seldomly overstepping into sap along the way. And the finale, tricky in its conception and wholly satisfying in its details, finds an upbeat tone even as it evades one's expectations. The way in which director Elizabeth Allen arrives at a denouement built out of truth and earned wisdom rather than a more typical fairy tale ending confirms the appreciable level of intelligence she has given the story. "Aquamarine" isn't exactly unique or superior to its influences—it's no "The Little Mermaid" or "Splash," after all—but as a live-action family feature capable of winning over ten-year-olds as well as forty-year-olds, the film is gentle-hearted and surprisingly sweet.