Hemingway uses what Walker Gibson, in "Tough, Sweet, & Stuffy: An Essay on Modern American Prose Styles," calls a "plain" or "tough" style. Hemingway was notorious for "tough talk" as an ambulance driver during World War I and newspaper man thereafter. To be sure, his journalistic style carried over into fiction. After all, Hemingway once admitted:
[I was taught] to distrust adjectives as I would learn to distrust certain people in certain situations.
William Faulkner even said, as a kind of backhanded compliment:
[Hemingway] had never been known to use a word that might send the reader to the dictionary.
In The Old Man and the Sea, Hemingway, himself an old man at the time, not only uses this simple, unadorned style to portray Santiago, but he also characterizes the old man the way The Gospels characterize Jesus, in a religious and ethical rhetorical appeal that highlights his suffering and adds to his lore.
Throughout the novella, Hemingway uses such rhetorical devices as: polysyndeton (lots of "and"), high frequency words, monosyllabic words, articles, action verbs and tense, simple sentences, and short, choppy, compound sentences (see below).
His narration is masculine (without being too macho), and heavily reliant on ethos in its rhetorical appeal and characterization of Santiago. Ethos, as you know, means "suffering," and it is the language of most fiction. It is obviously the language of The Gospels.
As with most of his writing, Hemingway uses an elliptical style, so what is not said is as or more important that what is said. This is especially true when Santiago is alone on the boat catching the fish and fighting off the sharks. He talks to himself, sure, but the reader must fill in the narrative gaps. In addition, Hemingway uses several Spanish phrases ("bodega," "aqua mala") and fishing terms ("skiff," "bonito") as devices of regional dialect and jargon, respectively, for added realism.
To build myth and romance, Hemingway uses many religious and cultural allusions and symbols, both ancient and modern. He references Joe DiMaggio, Hail Marys, John McGraw, the lions of Africa, the Detroit Tigers, the Yankees. All told, these function as a kind of allegory. Most critics agree that the marlin is Hemingway's book and the sharks symbolize literary critics.
Examine one of the novella's ending passages:
He unstepped the mast and furled the sail and tied it. Then he shouldered the mast and started to climb. It was then he knew the depth of his tiredness. He stopped for a moment and looked back and saw in the reflection of the street light the great tail of the fish standing up well behind the skiff’s stern. He saw the white naked line of his backbone and the dark mass of the head with the projecting bill and all the nakedness between.
He started to climb again and at the top he fell and lay for some time with the mast across his shoulder. He tried to get up. But it was too difficult and he sat there with the mast on his shoulder and looked at the road. A cat passed by on the far side going about its business and the old man watched it. Then he just watched the road.
This passage is written at a 4th to 7th grade reading level, about the readability of a newspaper. The sentences are long, but the sentence structure and word choice are simple. Each word has one or two syllables. There's very little adornment, few adjectives. The passage parallels The Gospels' account of Jesus carrying his cross to Calvary. It's heavy on ethos in its rhetorical appeal.
Hemingway makes skillful use of allusion in order to identify the alienation of Santiago from the community of fisherman, which then translates to man's alienation. For, through certain allusions, the reader deduces that Santiago with his "eyes the color of the sea" is clearly not Cuban, but Spanish. As part of the race of the conquerors, Santiago, therefore, is an alien in the humble fishing community.
In his essay, "Spain and Otherness in Hemingway's The Old Man and the Sea," Jeffrey Herlihy of Morningside College contends that through several allusions, Hemingway provides the Spanish background of Santiago forged a national identity in the Canary Islands. For, in an early dialogue with Manolin Santiago responds to the boy about how he work out of the Canary Islands, a Spanish archipelago,“When I was your age I was before the mast on a square rigged ship that ran to Africa.”
Underscoring Santiago's alienation from the community, he dreams frequently of
the white peaks of the Islands rising from the sea and then he dreamed of the different harbours and road-steads of the Canary Islands.