I believe that you are asking about the book The Lord of the Flies by William Golding. The boys must overcome quite a few obstacles on the island. Initially, the obstacles are all focused on basic survival and potential rescue. The boys must find access to fresh water, and they must figure out a food source of some kind. Fortunately the island has a fresh water source and a seeming abundance of pigs. The boys must also overcome the obstacle of needing a shelter. The boys are successful with that as well. Disease prevention is important, which is why Ralph sets up a place for the boys to go to the bathroom that would stay clean. In order for a chance at rescue, the boys need a way to signal passing ships or aircraft. Starting and maintaining a fire is a serious obstacle in the beginning of the story. As the story progresses, the main obstacle that the boys must try to overcome is fighting amongst themselves.