If you like The Tail of Emily Windsnap (Emily Windsnap #1)

For as long as she can remember, twelve-year-old Emily Windsnap has lived on a boat. And, oddly enough, for just as long, her mother has seemed anxious to keep her away from the water. But when Mom finally agrees to let her take swimming lessons, Emily makes a startling discovery - about her own identity, the mysterious father she's never met, and the thrilling possibilities and perils shimmering deep below the water…