Ernest Hemingway had a simple rule for writing: if you know something well enough, you can omit it, and the reader will feel its presence like the bulk of an iceberg beneath the water.
He called it the Iceberg Theory (or the Theory of Omission), and it’s perhaps the most powerful worldbuilding principle ever articulated. Show only the tip-10% of what you know. But you must know the other 90%.
This isn’t about being mysterious for mystery’s sake. It’s about creating depth that readers can sense but never fully see.
The Psychology of Hidden Depth
When you read a story where the world feels authentic, you’re not consciously cataloging all the details the author included. You’re sensing all the details the author didn’t include but clearly knows.
The paradox: The less you explain, the more real it feels.
This works because of how our brains process authenticity. In real life, we don’t experience exposition dumps. We encounter fragments-overheard conversations, worn objects, cultural assumptions never stated aloud. When a story mimics this fragmentary experience, our pattern-recognition systems register it as genuine.
Consider this exchange:
“The usual?” the bartender asked.
Marco nodded, already reaching for his wallet-the one without the photo anymore.
What do we know? Marco is a regular. Something happened with a photo he used to carry. The bartender knows him well enough not to need words.
What don’t we know? What was in the photo. Why it’s gone. How long he’s been coming here. The bartender’s name. Whether this is grief or relief.
That 90% of unwritten information creates gravity. The scene has weight because there’s clearly more to the story.
Hemingway’s Iceberg in Action: “Hills Like White Elephants”
The most perfect demonstration of this principle is Hemingway’s short story “Hills Like White Elephants”-a 1,500-word masterpiece about a couple waiting for a train in Spain.
The word “abortion” never appears.
But the entire story is about a man pressuring a woman to have an abortion. The tension, the power dynamics, the relationship’s trajectory-all visible in dialogue about drinks and hills and luggage.
What Hemingway shows: A couple having drinks, discussing whether the hills look like white elephants, talking vaguely about “an operation.”
What Hemingway knows (and we sense): The full history of their relationship. The man’s selfishness masquerading as concern. The woman’s devastation disguised as compliance. The impossibility of going back to how things were.
The story works because it’s mostly submerged. The reader does the work of understanding, which creates deeper engagement than any amount of explanation could achieve.
Building Your 90%: The Work No One Sees
Here’s the uncomfortable truth: The Iceberg Theory requires you to do massive amounts of work that will never appear on the page.
For worldbuilding, this means:
1. Know your world’s history
Even if your story takes place over three days, you need to know the preceding three decades (or three centuries). What wars shaped this culture? What technological breakthrough changed everything? What tragedy is everyone still processing?
You might never mention any of it. But when characters make offhand references or show unconscious biases, that history will make those moments ring true.
2. Understand economic systems
How do people make money in this world? What’s expensive and what’s cheap? What do people covet and what do they discard?
In The Expanse, the political tensions between Earth, Mars, and the Belt are driven by access to water and air. The authors (writing as James S.A. Corey) clearly mapped out the economics of space colonization, even though most of it stays submerged.
3. Map cultural assumptions
What does everyone in this world believe without question? What would be rude to say aloud? What’s so obvious it never needs explaining?
In Ursula K. Le Guin’s The Left Hand of Darkness, gender doesn’t exist in the same way. She doesn’t explain this every chapter. Characters simply behave according to their cultural norms, and we absorb the strangeness through accumulated detail.
4. Build physical geography
Where are the mountains, rivers, cities? What’s the climate? How long does it take to get from A to B?
Even if your story never includes a map, you need one. When characters discuss travel time or mention seasonal weather or reference regional differences, those details must be consistent.
The 10% You Show: Strategic Selection
If you know 100%, how do you choose which 10% to surface?
Show the details that:
1. Reveal character through interaction
Don’t describe your world in exposition. Show characters navigating it.
The elevator smelled like someone had covered up vomit with synthetic pine. Taren held her breath until the fourteenth floor, same as always.
We learn: The building is run-down. Taren lives on the fourteenth floor. This is routine, not exceptional. She’s adapted to unpleasant conditions.
2. Create friction or contrast
Surface the elements that surprise, conflict, or complicate.
In Snow Crash, Neal Stephenson shows us a future where the Mafia delivers pizza with ruthless efficiency, but the federal government is a joke. That contrast reveals everything about his world’s power structures.
3. Imply off-screen life
Choose details that suggest a world continuing beyond the frame of your story.
The morning news played in the background-another carrier protest in the Gulf, another negotiation breakdown. Marco turned it off. He already knew how that story ended.
What protests? What carriers? What gulf? We don’t need to know. We just need to sense that events are happening, and Marco is tired of them.
4. Feel lived-in
Show wear patterns, accumulated grime, repairs and modifications.
The Millennium Falcon is a perfect Iceberg. We see the worn-down, jury-rigged interior. We don’t need Han’s full backstory with the ship. The dings and tape and mismatched panels tell us everything: this ship has a history.
When the Iceberg Fails: Common Mistakes
Mistake 1: Knowing only 10%
If you haven’t built the submerged 90%, readers will sense the shallowness. The world will feel like a stage set-a facade with nothing behind it.
Mistake 2: Showing 50%
Some writers know their world deeply but can’t resist sharing. The result is fantasy novels with twelve-page prologues explaining the mythology, or sci-fi stories that stop cold for technology lectures.
If you find yourself explaining, you’re sinking the ship.
Mistake 3: Showing the wrong 10%
You can know your world’s complete economic system, but if you surface currency exchange rates instead of how poverty affects your protagonist, you’ve chosen poorly.
Always ask: Does this detail reveal character, create conflict, or imply depth? If not, it might belong in your 90%.
Practical Application: The Two-Document Method
Here’s a technique that works:
Document 1: The World Bible (Private) Write everything. The history, the economics, the geography, the culture, the magic system rules, the technological specs. This is for you. It can be messy, incomplete, contradictory. You’ll refine it as you write.
Document 2: The Story (Public) Write your actual narrative. When you need a worldbuilding detail, consult your Bible and select the smallest, most oblique reference that will work.
Over time, you’ll develop intuition for what belongs above the waterline and what stays submerged.
The Ultimate Test
Ask yourself: Could a reader write a PhD dissertation analyzing the unstated implications of my world?
If yes, you’ve built a proper iceberg.
The Lord of the Rings has inspired decades of academic analysis not because Tolkien explained everything, but because readers sense the depth he knew but didn’t show. He created languages he barely used. He mapped history going back thousands of years that appears only in fragments. He built theological systems that inform character behavior without ever being explicitly discussed.
Practical Exercise
Take a scene from your current work. For every detail you’ve included:
- Write three things you know about it that aren’t on the page
- Delete any explanation or exposition
- Replace it with a character’s unconscious interaction with that detail
Before:
The city had been destroyed in the war twenty years ago. Now it was rebuilding, but slowly.
After:
Taren stepped around the rubble pile-someone had planted flowers in it this year. Third building on this block to try that.
The second version shows you know the history (war, destruction, twenty years of slow recovery, community resilience, repeated attempts at beautification) without stating any of it.
Why This Matters
The Iceberg Theory isn’t about withholding information to be clever. It’s about respecting your reader’s intelligence and mirroring how we actually experience reality.
We navigate our world without exposition. We infer, assume, pick up context. When a story does the same, our brains recognize it as authentic.
Build your 90%. Show your 10%. Let readers sense the depth.
That’s when worldbuilding becomes world-feeling.
Next in the series: The Familiar Made Strange - How defamiliarization technique makes readers see ordinary worlds with fresh eyes.