The Tail of Emily Windsnap by Liz Kessler
Emily is a 12 year old girl who lives with her mother on a boat. Which doesn't make much sense since her mom avoids water all the time. It comes as a huge surprise when mom finally allows her to take swimming lessons.
On her first time getting into the pool, something strange happens and she can feel her legs fusing together. Emily, when submerged in water, becomes a mermaid. She doesn't think her classmates noticed, but now she knows she has to avoid the pool at all costs. But that doesn't mean she can't just jump off the boat at night and see what happens.
I'd say this was a middle grade reader's book. I expected to love it more, since it has always been my dream to become a mermaid. This felt more like if Scooby Doo was a mermaid, if that makes any sense at all. There was some excitement and adventure as Emily makes a mermaid friend and finds that she may be the subject of the merpeople's equivalent of an urban myth. Emily and her new mermaid friend become the equivalent of the "meddlin' kids" of the original Scooby gang, as they search for answers about Emily's parentage and try to match wits with the creepy lighthouse keeper.
I think kids from 4th grade to 6th or 7th might enjoy this story, but it may be a little too simplistic for readers older than that. I was hoping this was going to be one of those books that you can enjoy at any age, but it didn't work out that way for me. I think Emily is a cute character, but the whole crabby guy in the lighthouse plotline was less compelling children's story and more Saturday morning cartoon rerun.