Some antagonists can't be fought—they can only be survived.
It's common to hear "antagonist" and think "villain," but the two are not synonymous. An antagonist is just who or what is preventing your protagonist from achieving their goal. Often, that is a person and a bad one at that, but it can also be from a conflict type that has no personal stake in the game.
Like Mother Nature.
Your antagonist can come from any of the four basic conflict types, and they each focus on a different type of conflict opposition. We've discussed the person vs. society conflicts, and person vs. self antagonists, so let's look at the person vs. nature conflicts.
Person vs. Nature conflicts have often undefeatable foes to deal with, because they focus on taming the untamable or surviving the overwhelming threat.
A great example of a nature antagonist is a traditional disaster movie like Volcano.