With his marriage to Martha over and a divorce pending, Hemingway returned to Cuba. Mary soon joined him and fell in love with his cats, the ocean, swimming, fishing, and Cuba's tropical climate. On March 14, 1946, they were married in Havana. In August, on their way to a vacation in Idaho, Mary had an ectopic pregnancy and almost died, with Hemingway coming to the rescue. He was very good in a crisis, especially where his family was concerned. Hemingway loved Sun Valley and Ketchum, Idaho, with their magnificent scenery and hunting, and they later bought a house there.

An extended period of poor health for both Hemingway and Mary and a continuing series of losses as friends and family became ill and died now began. Hemingway had always had poor luck when it came to odd accidents--infant Bumby stuck his finger in Hemingway's eye painfully cutting the cornea, a skylight came down on his head in Paris leaving a nasty gash and a dramatic scar, he suffered four concussions in two years during World War II, he slid and fell on the Pilar, and the Hemingways' own plane and the rescue plane crashed during a safari in Africa in 1954. In each case he came out alive but not unscathed. Now severe headaches returned, he was gloomy and lonely, his blood pressure was very high, and he was overweight--a pattern that would continue the rest of his life with the addition of cholesterol and liver problems, depression, eventually diabetes, and the results of all those accidents and a lifetime of heavy drinking. During this period he was writing a novel about the happiness of the garden that a man must lose. After his death, a third of the manuscript was published as The Garden of Eden.

In January 1951 Hemingway began to write a story that had been ripening in his head since he first heard it in 1935. It was the story of an old "Cuban fisherman who fought a swordfish for four days and four nights only to lose it to sharks." (75) In 1936 Hemingway outlined the story "On the Blue Water" in Esquire. It would become the novella The Old Man and the Sea. The old man "knew he was going far out and he left the smell of the land behind and rowed out into the clean early morning smell of the ocean." (76) After a monumental struggle, he catches his giant fish, lashes it to his skiff, but sharks eat it on the way back to Havana. It was the ultimate story of "simple strength of character, deeper than his will. Hemingway seemed," Scribner felt, "to admire that in a man more than any other quality." (77)

Hemingway felt it was "the best I can write ever for all of my life." It is "an epilogue to all my writing and what I have learned, or tried to learn, while writing and trying to live. It will destroy the school of criticism that claims I can write about nothing except myself and my own experiences." (78)

Hemingway was amazed at how quickly and clearly he was able to write the story. At twenty-six, he had done the first draft of The Sun Also Rises in six weeks; at twice that age he completed The Old Man and the Sea in eight weeks. But he had had to rewrite his first novel completely. He had learned enough in twenty-five years so that he did not have to rewrite The Old Man and the Sea at all. (79) He wrote a thousand words a day for sixteen days, (80) a remarkable feat for someone who had written his editor Maxwell Perkins in 1944: "Charlie's [Scribner's, Sr.] ridiculing of my daily word count was because he did not understand me or writing especially well nor know how happy one felt to have put down properly 422 words as you wanted them to be. And days of 1200 or 2700 were something that made you happier than you could believe." (81)