Who or what is the protagonist?
Santiago, the old man, is the protagonist. It is his motivation that drives the entire story. He has a very strong motivation because he depends on fishing for his livelihood and he hasn't had any luck for a long time. The big fish is not the antagonist. This is a conflict of man against nature. Santiago is fighting the sea and the creatures in it. The big fish is the objective and would be called the MacGuffin by Hollywood film makers. Santiago manages to hook a big fish, but then he has to fight off the sharks in order to keep his prize. In the end he is defeated. The sharks have devoured the fish and left him with only the skeleton. True to one of Hemingway's favorite themes, the old man is beaten but does not surrender.