Surfacing — Emma Shelford

The more marine biologist Corrie Duval learns about the mysterious sea creatures she discovered, the more questions she has. Where are the creatures coming from? How are they related? And what is Zeballos Artino hiding?

Zeb wishes he had the answers to Corrie's questions, but there is so much he can't say, and even more that he doesn't know himself. The glimpse of the woman in the water plagues him with riddles he can't decipher, and his late father's translated notebook provides frustrating clues.

But when Zeb discovers someone attracting mysterious creatures with the same sonar device installed on his own boat, he and Corrie must race to uncover the truth before the world of the creatures is exposed.

This is book three of the Nautilus Legends.