The Atlantis Twins: The Mermaid Curse Book One

Alysa Grey is certain her lost twin sister is alive even though Hawaii search and rescue gave up years ago. Meanwhile, her obsession with the ocean and strange ability to heal from injury threatens to end what passed for normal teenage life. When she meets Nate, a handsome surfer, he presents the opportunity to escape her woes. But Nate is not who he seems and Alysa ends up trapped on an aging ship bound for a mysterious island. She will do anything to find her lost twin sister. But first she must lose herself.