Ernest Hemingway was initially involved in the production, although the extent of his participation after selling his book's film rights to Warner Bros. was to go marlin fishing off the coast of Peru to try to find a fish suitable for use in the film. In the end, the producers used a rubber marlin and stock footage of marlin fishing in which Hemingway didn't participate. After seeing the film, Hemingway expressed his disappointment, remarking that Spencer Tracy looked less like a Cuban peasant fisherman than the rich actor he was. Nevertheless, Tracy earned an Oscar nomination for the role.
Ernest Hemingway can be seen sitting in the cafe in the final scene wearing a tan baseball cap and conversing with other fishermen. This was his movie debut.
Mary Hemingway, who was Ernest Hemingway's fourth wife and later became his widow, plays the blonde tourist at the end of the film. She crosses the street and takes a seat in the café, but speaks no lines.
In 1952, Humphrey Bogart attempted to purchase the film rights to Ernest Hemingway's novel through his production company, "Santana Productions." Bogart identified strongly with the character of the old man and very much wanted to play him, with Nicholas Ray directing. Unfortunately, Bogart was unsuccessful in securing the film rights, and the film wasn't made until the year following his death, with his close friend Spencer Tracy starring.
Spencer Tracy flew to Cuba from Los Angeles to meet Ernest Hemingway and get his approval as Santiago.