Explain what it is about "The Snows of Kilimanjaro" by Earnest Hemingway that makes it Naturalistic/Realistic?

One critic said, "Realistic fiction is often opposed to romantic fiction: the romance is said to present life as we would have it be, more picturesque, more adventurous, more heroic than the actual; realism, to present an accurate imitation of life as it is."

The main way Hemingway avoids romance in "The Snows of Kilimanjaro" is through his authorial voice and writing style, which is so plain and straightforward that it breeds honesty.  Hemingway distrusted adjectives; he feared they were merely for emotional adornment and exaggeration.  Instead, he wrote is a sparse, journalistic style: simple words and sentences, lots of first person pronouns, a very informal causal male voice to establish ethos, or credibility and trustworthiness of the writer or speaker.

George Plimpton said of Hemingway's style:

‘‘principle of the iceberg . . . for seven eighths of it is under water for every part that shows.’’

So it is with Hemingway: he only tells what he has to tell; the rest is inference and induction (we have to fill in the missing pieces).

Hemingway wanted his readers to know exactly who wrote these stories.  He did not play around with point of view, like Faulkner, and present unreliable narrators.  Hemingway's simple consistent style let his audience know that he had climbed the mountain, seen what he had seen, thought about it for a long time, and carefully presented it to us in an objective voice that neither tried to trick nor add to the facts.  And, most importantly, he omits any kind of authorial voice that tells what to believe or how to interpret it.  In short, he trusted his readers.

Example:

He lay then and was quiet for a while and looked across the heat shimmer of the plain to the edge of the bush. There were a few Tommies that showed minute and white against the yellow and, far off, he saw a herd of zebra, white against the green of the bush. This was a pleasant camp under big trees against a hill, with good water, and close by, a nearly dry water hole where sand grouse flighted in the mornings.

Notice the bare-bones writing.  It is with zest, but without sentimentality.