why does Santiago idolize Joe DiMaggio? How does he draw strength from this hero? How do his thoughts of DiMaggio's struggles help him battle the elements/ antagonists of society and nature?

Dimaggio is a recurring symbol throughout the story. He was a partially handicapped icon of baseball. He lurks in the old man's dreams and visions. Dimaggio is seemingly from Santiago's home-land and like the old man struggles through pain for glory that is rightfully his. AS Santiago's left hand cramps and fails him, he recalls Dimaggio's "bone spur". This gives Santiago a sense of his own heroic realism to bear his own pain through all 9 innings of his battle with the Marlin.