Aquamarine is the story of Claire (Emma Roberts) and Hailey (Joanna “JoJo” Levesque), two 13-year-old best friends who embark on the adventure of their lives when they discover a mermaid (Sara Paxton) named Aquamarine in a swimming pool. Aquamarine had washed ashore after a big storm battered the small town Florida beach club where Claire lives with her grandparents. Claire and Hailey are trying to come to terms with Hailey’s impending departure: she’s moving to Australia with her marine biologist mother after this last weekend of the summer.

The beautiful, blue-haired, 18-year-old mermaid swam away from home just before her arranged marriage, in search of real love. If she can prove to her father that love is not a myth, he’ll let her out of the underwater wedding, but he’s only giving her three days. Aqua enlists the help of Claire and Hailey, who are self-styled relationship experts – educated from the pages of magazines that they read and quote daily.

Aqua sets her sights on the Capri Club’s lifeguard, Raymond Calder (Jake McDorman). And when Aqua promises to grant Claire and Hailey the wish of their choice if they help her reel in Ray, the girls jump at the opportunity – because unless something magical happens, Hailey will be moving.

The girls hope that as long as Aquamarine can keep her land legs and avoid sprouting her massive, mythological tail, everyone will see their wishes come true. More importantly, they learn some important lessons about the power of friendship, the true magic of love – and the importance of standing on your own two feet.