Sharks & Boys by Kristen Tracy

When 15-year-old Enid Calhoun follows her boyfriend Wick to Maryland for a party, fearful that he might be intending to cheat on her, she finds herself sneaking on board a houseboat where Wick and his friends plan to have a wild night. But before the boys discover their stowaway, a hurricane strikes, and the teenagers are carried miles from the shore and shipwrecked.