Emily Windsnap and the Castle in the Mist

Everybody has a secret. Mine's a little different, though. I didn't even know about it until the first day of swim class in seventh grade. You see, I'd never been allowed to go in the water before. As it turns out, swimming comes naturally to me. Very naturally. In fact, so naturally that you might even say . . . well, it's true.
 
Here's my secret: I figured out that I'm a mermaid.