Maile and the Spinner Dolphin — Michael Herr

Maile had been looking forward to leaving elementary school behind and going into 7th grade with her best friend. She knew they would have it made. But then, on the first day of the new school year, things went wrong. In fact things went from better to worse. And when Maile decided to cut school and go to the beach, they went from worse to absolutely horrible. Now Maile is faced with a hungry shark, and no one around to help her. Except maybe, maybe someone from her past can reach out to her. This is the first book of the Maile series set on the island of Kauai.