Where Santiago found the marlin was in somewhat shallow water where it was closer to Santiago (the creator). The marlin was tempted with the hook like Adam and Eve were tempted with the fruit from the tree of the knowledge of good and evil, and eventually gave in and took the bait (Adam and Eve partaking of the fruit). Once the marlin realized it was hooked it started heading for deeper water to hide just as Adam and Eve hid from God. As the fish got deeper it naturally got darker, resembling man running away from God trying to make their sin unnoticeable.
Along with swimming to deeper water, the marlin had to pull the boat behind him as a burden that he had to carry because he was trying to escape from his mistake. The old man wondering what the fish was doing said "If you're not tired, fish, you must be very strange. " (The Old Man and the Sea, page 67, paragraph 4) just as God would wonder about man running and running from Him and never seeing the truth that is right in front of him. A good amount of time goes by and they're in deep waters where sharks attack the fish and do a little damage to the boat.
The attack on the fish is like man going through the tribulation but evil doesn't just do damage to man but to God too because He cares about us and doesn't like to see us suffering. At the end right after the old man sees the lights from the city on the horizon the sharks attack the fish again. The old man fought the sharks and finally got them to leave but with nothing but the carcass of the fish. In the same way, God will fight for us and scare the enemy off so that He may have us (those who accepted Him) like the old man had the memory of what the fish was like. In the night sharks hit the carcass as someone might pick up crumbs from the table. The old man paid no attention to them... " (The Old Man and the Sea, page 67, paragraph 3) because it is only the flesh that remained. Another object in the story that shared similarities to life was the sea. The old man had been fishing for most of his life so he was well acquainted with the sea. Yet still that one time that he went out and he got a glimpse at what he desired he went after it and in this case cost him almost everything. While pursuing his desire the sea shook him, beat him, and gave him some unexpected turns.
Some examples of those where when the fish dragged him out to sea further and further, when he had to fish for food because he ran out, when the fish kept going after the old man though it would be out of energy, when the sharks attacked, or after all the time he spent out at sea trying to catch the fish, he had nothing but the carcass to show for it. It is the same with life. Humans get into their routines but 100% of those humans get something thrown at them that they didn't see coming. Like a car crash resulting in death, heart attack, or maybe it is family members that just got the news that a loved one committed suicide.
The biggest similarity between life and the sea is that in the beginning of the story the old man would take the boy out with him to teach him techniques of how to fish while in life the person you look up to, most likely the father figure, can tell you what to do incase something happens or if something happens again but the pupil will learn from the father the most when they are in real time situations and the pupil gets to see how the father handles the situation. Based on what the pupil sees is where he or she will ultimately learn from that father figure.
So while the boy's parents where at home telling him not to go fishing with the old man because he is bad luck, the old man takes the boy out into the world and actually shows him how most everything is done rather than just telling him. The poor and the rich town people in the story also share similarities. Since it was a small town by the sea most if not everybody fished. The rich would fish as a way to relax while their business inland was being run by one of the citizens in a lower money bracket. While the poor were fishing to stay alive. It was their means of survival.
Both the rich and the poor came in after fishing for the day and either turned in their fish for money or took it home to be eaten. Even though both classes of society were quite the opposite they almost did the exact same things because the town was so small and there was hardly anything to do. There are many different objects and characters that Hemingway wrote in The Old Man and the Sea that share similarities among symbols and some of them are how the marlin represented life, the sea also represented life, and how the rich and the poor were similar beyond society saying they are opposites.
Hemingway used many symbols within his story and because no one has the same point of view, the reader is left to interpret those symbols on how they see it. All the symbolism in the book makes it a great book for all ages. For the kids it is a nice easy read but for the older generations there can be a lot of information found on the author, life, and many other topics.