You may choose to write about a number of things. Firstly, you can say how, at first, you enjoyed the freedom, and the nice weather, and the sea. As time went by you can start to show how your initial enthusiasm disappeared, and how you had to adapt while waiting for help (i.e. try and find shelter, some food, learn how to hunt, catch fish etc). Eventually you come at the top and see...? You may chose to have a depressive ending, or an optimistic (e.g. you see a ship approaching).
Hope that gives you some ideas!
