In The Lord of the Flies, the setting for the story is a tropical island. This island is largely symbolic of the Garden of Eden in its state of perfection prior to the fall of man. The island is described as untouched, and affording bountiful food. It represent the possibility for the boys to create a civilization anew, the potential for the realization of a harmonious state between men and between man and nature.
Just like in the story of the Garden of Eden, we see man failing to recognize this potential, and instead being influenced by the darker side of his nature. As a result the boys are metaphorically cast out from the paradise offered to them and descend into an existence dominated by suffering.