When Santiago wakes the next morning, he goes up the road to Manolin's house to wake him, as he does every morning. Santiago apologizes for disturbing Manolin's sleep, but Manolin responds, "It is what a man must do."
Both Manolin and Santiago take pride in meeting what they see as the requirements of being a man—duty, honor, facing difficult challenges without complaint.
Santiago drinks his coffee, thinking how he will not eat all day because eating has bored him for a long time. Manolin helps Santiago load his boat, and they wish each other luck. As he rows into the water, Santiago hears the splashes in the dark of other boats nearby, but no voices. Fishermen rarely speak to each other in their boats.
Santiago's boredom with eating suggests his boredom with life—he is no longer interested in everyday pleasures. The habit of silence among fishermen and the fact that Manolin no longer fishes with reinforce how alone Santiago will be at sea.
Santiago rows over "the great well," where the ocean suddenly drops to 700 fathoms and where many fish congregate. He hears flying fish flapping around him. He thinks of these fish as his friends. He feels sorry for the birds trying to catch the fish and failing, knowing how hard these birds must work to survive.
Santiago thinks of the sea as "la mar," as a woman who can give or withhold great favors and changes with the moon. He doesn't understand the younger fishermen. They use motorboats instead of skiffs and call the sea "el mar," using the masculine noun as if the sea is their enemy.
Santiago decides to fish past the deep wells, because he caught nothing in the wells the previous week. By the time the sun comes out, he has found a good spot and has his bait in the water, on lines pre-measured to fall to different specific depths. He is proud that he keeps his lines straighter than any other fisherman and does not let them drift with the current. As the sun rises, he marvels at how his eyes are still good despite years of strong sun.
Santiago takes pride in his craft—unlike the younger fishermen who rely on strength and the brute force of technology. Santiago's clear vision symbolizes the wisdom he has gained as he aged, as well as his strength of mind.
Santiago sees a sea bird diving into the sea in the distance. He rows toward it, farther out into the ocean, knowing the dipping means the bird has seen fish. He sees a school of dolphins chasing flying fish nearby, another sign of fish, but arrives too late. He knows his big fish is out there somewhere.
Santiago is able to read the signs of nature. His initial failure (after 84 days of previous failure) is not enough to dampen his optimism.
In the late morning, one of Santiago's lines suddenly tightens and Santiago pulls in a silver, 10-pound tuna. He observes out loud that the tuna will make a beautiful piece of bait, then wonders when he began talking to himself. He concludes that it must have been when Manolin left, and thinks that if the other fisherman heard him they would think he was crazy, though he knows they would be wrong.
Santiago's small catch (his first in 84 days) marks the turning point in his luck. Talking to himself is a way to avoid loneliness and despair. Talking out loud as if Manolin was in the boat allows him to bring his friendship with Manolin with him even though Manolin isn't there.
Around noon, Santiago feels a tentative pull on one of his lines. He thinks it must be a marlin eating the sardine bait, 600 feet below. The marlin leaves, and then comes back, and Santiago becomes more and more excited, judging from the strength of the pull that the marlin must be a huge fish. Finally, when he thinks the marlin has gotten hold of the hook, Santiago tries to pull the marlin up. The fish doesn't budge.
Many years of fishing have honed Santiago's intuition and his ability to interpret even the smallest signs in the sea. From the strength of the pull he can immediately estimate the size of the fish. For the first time in the story he becomes animated instead of tired, acting much like a young man.
The marlin starts to move away, pulling Santiago's skiff with it. The marlin pulls the skiff all day, as Santiago braces in his skiff and holds tight to the line. The marlin continues to tow the skiff until Santiago can no longer see the shoreline of Cuba anymore. He is confident, however, that when the sun goes down he will be able to find his way back by following the glowing lights of Havana.
Pulled out so far that he can't even see the land, Santiago faces a fish far stronger than he is. As an old man with no available help, Santiago faces a serious and potentially dangerous challenge. But his pride won't allow him to accept defeat.
When the sun goes down, Santiago wishes Manolin could see his big catch and help him drag the marlin out of the water. But then he begins to pity the marlin, wondering if the fish is old, like him. He can tell by the way marlin took hold of the bait that it is a male fish. He realizes that he and the marlin are "joined together" far out in the ocean, "beyond all people in the world," with no one who can help either one of them.
Santiago remembers when he and Manolin caught a female marlin, one of a pair. She fought desperately, and the entire time she was fighting the male fish never left her side. When Santiago dragged the female into the boat, the male marlin followed the boat.
The male marlin's reaction to his female companion's capture mirrors Santiago's own loneliness and sadness over his wife's death. Once again, this highlights the connection between men, and Santiago in particular, and nature.