This comical and heartfelt picture book is a winning celebration of invention, creativity, and friendship. With gorgeous underwater scenes and a crowd-pleasing tale, this is one little mermaid who is here to make a splash!

New York Times bestselling author Kelly DiPucchio and illustrator Raissa Figueroa would like to introduce Oona —the big wide sea's littlest mischief-maker.

Oona and her best friend Otto love to search for treasure…and often find trouble instead.

Messy trouble.

Tricky trouble.

Even shark-related trouble.

That's never stopped them before, though!

After all, no proper treasure hunt is without some adventure. But when the greatest treasure yet is stuck in a deep, dark rift, Oona's not sure if she can dive right in. What might be waiting for her in those unknown waters?