Sharks, shipwreck, and sunken treasure in this action packed survival series from bestselling and award-winning author Gordon Korman.

What lies in the deep? Not just coral and sand. Not just undersea creatures that have never seen the light. No, the deep holds something even more mysterious and valuable.

Kaz, Dante, Adriana, and Star started the summer thinking they were going to study marine life. Now they've found sunken treasure. And they're not the only ones who want to keep it.