This is a novella filled with lots and lots of conflict of all kinds. (It is called The Old Man and the Sea, of course, which represents a kind of conflict right from the beginning.) Anything which is Santiago against the fish is conflict. For example:
Just then the fish gave a sudden lurch that pulled the old man down onto the bow and would have pulled him overboard if he had not braced himself and given some line.
Other external (physical) conflicts include man vs. shark, man vs. hand, man vs. hunger, man vs. sleepiness...and plenty more.
Santiago also experiences an inner conflict in several ways. He has to convince himself to keep going despite the pain. He fights his daydreaming in order to stay as focused as he needs to be. He also wavers in his resolve to kill this fish for which he has such respect.
Then he was sorry for the great fish that had nothing to eat and his determination to kill him never relaxed in his sorrow for him.
Santiago also has a man vs. society conflict, a society which calls him unlucky and old and not a good fisherman anymore.
This entire reading is a story about conflict and how to persevere in the face of trying circumstances and against all odds.