Determination: Battle with the marlin was not only brute force but also willpower. The old man has immense amounts of endurance, as can be derived from how he withstood physical pain, hunger, and isolation.
Strength: Physical strength is a part of this as well as his strength in knowledge for fishing. As he is not young, Santiago uses as much of his strength as possible but later depends on his vast experience with fishing.
Pride: In the beginning Santiago was prideful and wanted to prove himself as a fisherman to his village. Later on, after the marlin experience, Santiago became more humble and realized that proof is not really need but rather the thrill of the experience itself. “You did not kill the fish only to keep alive and to sell for food, he thought. You killed him for pride and because you are a fisherman. You loved him when he was alive and you loved him after. If you love him, it is not a sin to kill him. Or is it more?”
Respect: What made the battle with the marlin that intense was because the stakes were so high. The old man wants respect from others for catching such a huge fish and likewise the old man respects the marlin as he fights against the marlin with strength and willpower. Even in the story, Santiago clearly says his respects for the marlin's own strength and will to escape. “Fish," he said, "I love you and respect you very much. But I will kill you dead before this day ends.”
Friendship: The old man's relationship with Manolin can be described with this. Manolin cares and worries for Santiago while Santiago accepts Manolin's company and sentiments. Manolin could have easily forgotten about Santiago but chose to stay as Santiago's apprentice.