Spencer Tracy plays Cuban fisherman Santiago, isolated at sea in a small little fishing boat reminiscining about old times and waiting for a catch. One day he's stunned to come across a huge marlin who circles his boat. Santiago harpoons it; and eventually attracts a few sharks on his way home. The sea struggles (between Spence and the fish) are exciting, and Dimitri Tiomkin's score is really good. Thanks to director John Sturges, who is at his best with action sequences like this. There are many moments of narration by Tracy; the words come directly from Hemingway's book. I was not convinced that Spence was a Cuban. But the movie, like the novel, is very allegorical and not everything makes sense. Several flashback sequences feature symbolic images of lions and fish, and in one scene we're taken back to an arm wreslting match between Spencer and a man who is referred to as a "negro" multiple times. 
In the end, the old man returns to his village exhausted, and is reaquainted with his young Cuban apprentice, a boy named Manolin, but all the old man can do is sleep. There was a made-for-TV 1990 version with Anthony Quinn.Oscar win for best Original Music Score