The question of the old man's success on his last fishing trip is deliberately left double-edged by Ernest Hemingway in The Old Man and the Sea. Judged by results, Santiago fails; judged by spirit, he triumphs.
The material failure. Santiago sets out after eighty-four days without a catch, sails far beyond the other boats, and hooks a giant marlin longer than his skiff. For two days and nights he battles it, and at last kills it and lashes it to his boat. But on the long voyage home the blood of the marlin draws sharks. One by one they tear away the flesh until, when he reaches shore, nothing is left but the great white skeleton, the head and the tail. In practical terms the trip is a failure: he brings home no saleable fish and returns as poor as he set out, his hands cut and his body exhausted.
The moral and spiritual success. Yet in every way that matters to Hemingway, Santiago succeeds. He proves his endurance, courage and skill by catching the greatest fish of his life and by fighting the sharks to the very end, refusing to give in. His often-quoted resolve, that a man can be destroyed but not defeated, is vindicated: he is destroyed of his prize but not of his dignity. He keeps his pride, his self-respect and his bond with the boy Manolin, who weeps for him and vows to fish at his side again. The skeleton itself, admired on the beach, is proof of the magnitude of his achievement.
Balanced judgement. To the extent that success means profit or a fish to sell, the trip is a total loss. But to the extent that success means proving one's worth, showing unconquerable courage and winning renewed love and respect, Santiago is wholly successful. Hemingway's point is that true victory lies not in the reward kept but in the greatness of the struggle endured.
Therefore the old man was successful to a very high degree in spirit, even though he failed entirely in material terms.