Sunken Souls by Erin Hayes

Our deepest, darkest fears don’t just live in our nightmares. They’re under the sea. And they want me. Growing up, my parents just had one rule: stay out of the ocean. Which was pretty easy when the closest beach was a thousand miles away. My days are spent at swim meets and hanging out with my only friend Dylan who I may or may not have a crush on. All that changes when I go off to college in Hawaii and my plane falls out of the sky and into the Pacific Ocean. I should have been fish food. Instead, I wake up to a world I never knew existed. Mermaids and kelpies and krakens and more — they’re real and more deadly than you can ever imagine. And then there are the exiled sirens of the deep. They’ve been planning a war since the moment I was born. And it looks like I’ll have to be dragged further and further to their depths to stop them. If I even want to, once I learn the truth.