Magic Island is a 1995 direct-to-video film starring Zachery Ty Bryan as Jack Carlisle, the film's young hero. Jack's feeling a little neglected at home, especially because his mom has had to work extra hard after his dad left. When Jack's mom has to cancel on their special dinner night, Jack decides to run away from home. Lucretia, their housekeeper, manages to stop Jack from leaving, and encourages him to read a book, "Magic Island", that was written by one of her ancestors.
Only thing this, when Jack opens the book to read it, the pictures come alive and suck him into the book itself. Jack arrives on the Magic Island, right in the middle of a fight between Prince Morgan and his crew, and Captain Blackbeard and his pirates. They're after the treasure on Magic Island, and despite Jack's skepticism, he's drawn into the adventure and plays an important role in helping Morgan reach the treasure before Blackbeard does.
Along the way, Jack falls into the ocean and almost drowns (which is how it usually goes) and is saved by a mermaid, Lily. As reward for saving a human, Lily is able to gain legs for a short while, and she happily joins them on their adventure.
It's a cute, simple film, with some straightforward laughs and the actors hamming it up because if you're gonna have an adventure on a Magic Island you might as well just go the nine yards. Lily is younger than most of the other live-action mermaids depicted on screen, and she's a sweet, excitable young lady, though she has her sassy moments as well.