The struggle between Santiago and the great marlin forms the heart of Ernest Hemingway's The Old Man and the Sea. It is at once a gripping physical contest and a profound test of the old fisherman's courage, endurance and dignity.
The hooking and the long haul. After eighty-four days without a catch, Santiago finally hooks an enormous marlin far out in the Gulf Stream. The fish is so powerful that instead of being pulled in, it tows the skiff for two days and two nights. Santiago cannot see the fish for most of this time; he can only hold the line across his back and shoulders, giving line when he must and taking it back when he can. The strain cuts his hands, cramps his body and exhausts his ageing frame.
Endurance and suffering. The struggle becomes an ordeal of physical suffering. His hands are lacerated by the line, one hand cramps and "betrays" him, his back aches and he goes without proper food or sleep. Yet he refuses to give up, repeating his resolve to prove "what a man can do and what a man endures". His stamina is drawn partly from memories of his youthful strength, such as the great arm-wrestling match he recalls.
Respect for a worthy adversary. Santiago comes to love and admire the marlin, calling it his brother and pitying it even as he is determined to kill it. The fish is noble, beautiful and stronger than any he has known, and the contest is one of mutual worthiness rather than mere hunting. This respect ennobles the struggle and gives it a spiritual dimension.
The kill and its bitter aftermath. At last the marlin circles closer and Santiago drives his harpoon into its heart, killing it. He lashes the huge fish alongside the skiff to sail home in triumph. But the victory is short-lived: sharks, drawn by the blood, attack the carcass, and despite Santiago's desperate defence they strip the marlin to a skeleton. He reaches shore with only bones to show for his heroic effort.
Meaning of the struggle. Though Santiago loses the flesh of his catch, he is not defeated in spirit; "a man can be destroyed but not defeated". The struggle affirms human courage, perseverance and dignity in the face of a merciless nature.
Santiago's fight with the marlin is thus both a thrilling sea adventure and a moving parable of the unconquerable human spirit.