Endless Blue Beneath (en Inglés) - Shannon English

She has become a monster of the deep—a mermaid.

Despite the horror of her new appetites, Eppie learns to love this strange second life. The mermaid colony is mesmerizing and Eppie’s new sisters are fiercely loyal. And when Eppie meets Marie, a stunningly beautiful mermaid with a past as shadowed as her raven-black scales, she finds she no longer needs to resist the desires that were denied to her on land. 

But dark sails are on the horizon. The mermaid hunters are coming, armed with cannons and Biblical wrath. Eppie must decide whether to protect the new, monstrous family she’s found or leave it all behind for a chance to live above the waves once again.