Santiago's exact feelings and attitude toward the sea are never expressly mentioned in the text of this novel. However, through context clues, we are able to determine that he loves his life as a fisherman (or at least had loved it when he was regularly catching fish and the other fishermen didn't look at him with pity as if Santiago were old and washed up), and he has a healthy respect for the sea and the creatures which live in it.
We know from the book that he is an experienced fisherman and that he knows many tricks of the trade...this indicates that he has fished for a long time, if not his entire life, and most people don't work horribly dangerous jobs if they didn't like some aspect of the job.
Santiago recounts one story regarding how he once caught and clubbed to death a female marlin while her mate never remained faithful and swam beside her and the boat. “That was the saddest thing I ever saw,” the old man comments. “The boy was sad too, and we begged her pardon and butchered her promptly.” This is a prime example of Santiago's respect for the sea and the creatures within it. He realizes that some of the fish have to die in order for him to make a living and also to provide for his family.
Santiago remains determined to succeed, and even after coming into port with nothing but the skeleton of the great fish, he declares he will go back out the next day and fish again. All of this is not just for his reputation, so we must also conclude that the loves his life and his job. Therefore, he must also love the sea.