An antagonist in a work of fiction is defined as "the character who opposes the hero, or protagonist. The antagonist, when there is one, provides the story's conflict." However, the antagonist does not necessarily have to be a living person. In this instance, one could argue that the true antagonist of the story is nature and the forces within it. Not just physical nature but human nature as well. Examples of this are the weather elements, Sam's family, and Sam's own internal feeling - loneliness and fear. This all provides Sam with many obstacles but also with plenty of opportunities to persevere.