Oceanheart

Wynn is swept into an island world of crystal seas, deep jungle and strange inhabitants. But it's no island paradise. Paradise doesn't have poison masters called the Teeth and it doesn't have Sorrowmaker patrolling the reef.
If Wynn wants to save her sister, she must find the Oceanheart. But the islanders don't trust her, the Teeth are after her and just who, or what, is the wild boy, Soran?