Despite the initial idea that you are stuck on an island without any food, there is actually a pretty good amount of options for you. Clams, Mussels, Sea Weed, and fish are all there for the taking. Mussels and Clams that are hard to open are typically good to be eaten- avoid eating ones that open with ease. Try your hand at some fishing, and explore the region to see if you can find any fruit. When unsure if fruit or vegetation that you find is poisonous, try rubbing it on the back of your hand to see if you develop any sort of reaction BEFORE eating it.