My good little mermaid

Fionna is a mermaid who has always wanted to go to the plan but something has got in the way. a Giant storm comes a wrecks haveck on a ship sailing to an uncharted island. Fionna goes and saves someone on the ship. Who will it be what mysterys will this island hold read to find out
Disclaimer I do not own adventure time. If I did there would be more fionna and came episodes. I do own my story and any new characters add