I would say that The Old Man in the Sea is much more about struggle or the struggle WITH ambition than it is about ambition only. By saying, "Santiago struggles with ambition" makes him sound arrogant, which he is not.
Divide your paper into two parts: struggle and ambition. Look for ideas first. Then find quotes and facts as support. Then, synthesize all the ideas, quotes, and facts into topic and clincher sentences. Voila! That's the outline of your paper.
Santiago struggles throughout the book. He struggles with his age, his bad luck as a fisherman, his peers who taunt him, his role as a teacher of Manolin, his relationship with his daughter. And that's all on the island.
At sea, Santiago struggles with nature: the marlin, the sharks, the ocean, and the weather. But, he loves nature: the sea is his mother, and the fish is his brother. Santiago hates sharks: they are the only evil in the book.
Mostly, he struggles with himself: his old hands, his arms, his strength, his dreams, his courage.
Santiago is not prideful: he has no false ambitions. His ambitions are realistic and humble. He wants to go far out and catch a big fish. He wants to end his bad luck streak. He wants to end his suffering. He wants an honorable death for the fish. Like a Christ-figure, he knows he is destined to suffer, and he suffers humbly, without regret.
Santiago's struggles and ambitions are mirrored by Hemingway the writer. Hemingway is like Santiago, in that he is struggling to write the book itself (the marlin). He is struggling against literary critics who try to tear his book apart (like sharks). Overall, Hemingway is trying to show the sufferings of an artist through the allegory of a fisherman.
*The Old Man and the Sea uses the omniscient, or "all-knowing," point of view of the author, who acts as a hidden narrator. The omniscient point of view enables the author to stand outside and above the story itself, and thus to provide a wider perspective from which to present the thoughts of the old man and the other characters. Thus at the beginning of the tale, the omniscient narrator tells us not only what Santiago and the boy said to each other, but what the other fishermen thought of the old man. "The older fishermen looked at him and were sad. But they did not show it."
Santiago is the protagonist of the novella. He is an old fisherman in Cuba who, when we meet him at the beginning of the book, has not caught anything for eighty-four days. The novella follows Santiago's quest for the great catch that will save his career. Santiago endures a great struggle with a uncommonly large and noble marlin only to lose the fish to rapacious sharks on his way back to land. Despite this loss, Santiago ends the novel with his spirit undefeated. Depending on your reading of the novel, Santiago represents Hemingway himself, searching for his next great book, an Everyman, heroic in the face of human tragedy, or the Oedipal male unconscious trying to slay his father, the marlin, in order to sexually possess his mother, the sea
the old man's battle is not only a battle of strength,but a battle of wills.Hemingway spends a good deal of time drawing connections between santiago and his natural environment and a destinction between two types of success,outer,material success and inner,spiritual success