An aging Cuban fisherman struggles against a giant marlin in the Gulf Stream, testing his physical limits and resolve. Santiago, a veteran fisherman who has gone eighty-four days without a catch, ventures far into the deep waters to reclaim his reputation. He faces the immense physical strain of battling a marlin that outweighs his small skiff, while contending with the isolation of the open sea and the encroaching threat of sharks. The narrative is presented in a sparse, third-person limited perspective that focuses intensely on the sensory details of the struggle and the internal monologue of the protagonist.

Readers and critics frequently analyze the text for its stark, economical prose and its philosophical implications regarding human struggle. Discussion often centers on the symbolic weight of the marlin and the protagonist's unwavering dedication to his craft despite his physical decline. Many highlight the effectiveness of the atmospheric setting, which transforms a simple fishing trip into a meditation on dignity and loss. The balance between the visceral action of the hunt and the quiet, introspective moments of the fisherman is often cited as a defining characteristic of the work. Scholars and general readers alike continue to debate the moral dimensions of the conflict between the man and the sea.