You play as a mermaid named Naija. Yup, you read that right, and you have an epic quest/destiny/thing to go on. Using the power of your voice and mystical songs, you can solve puzzles, defeat enemies, and cook food. Yes, that does not sound very good, but I felt that it was definitely worth the time I played. It has great underwatery visuals and music (as you would hope...being that singing is a primary mechanic) I plan on playing more. Also, I was going to put down money that the narrator was the same person as in the new Tomb Raider game. I was super wrong. Sorry everyone.
It's pretty cheap on Steam, but it's also available on the iPad, which sounds like would fit it well.