Three Knocks Below

Silence has a texture under the sea. It isn’t empty — it breathes. It hums against the steel, curls into the corners, whispers in your skull until you start to hear your own blood. We were two miles beneath the surface when I heard it.

Three knocks.

Measured. Solid. It reminded me of the way my Grandpa used to knock on my door after he would make the long drive to see me. I sat up in my bunk, heart thudding so hard I felt it in my teeth. No one should’ve been awake except Reyes on night watch. The rest of the crew slept in their metal coffins, their breath feeding the recycled air system.

The clock read 02:46.

Three more knocks. Louder now, on my door.

I stared at it — at the trembling hinge, the faint echo inside the walls — and said, “Who’s there?”

Nothing. Of course it was nothing. A wave of self-embarrassment after realising I was calling out to nothing. Just the deep, eternal hum of the Odyssey and the far-off groan of the hull flexing against pressure that could crush us in a heartbeat. I stood, bare feet against cold metal, and opened the door. The corridor glowed dull red under the night lights. The air tasted of oil and salt. No one. Just as I expected. Only three small wet circles on the door — like fingertips. I touched one. It was freezing. Reyes jumped when I entered the control room.“Jesus, Harper,” he said, clutching his chest. “What are you doing up?”

“Someone knocked on my door.” He frowned. “No one’s moving around. Everyone’s accounted for.”

“Then what did I hear?”

He hesitated, then tapped the sonar display. “I’ve been getting something weird. A return echo — small, moving along the hull.”

The pulse flashed across the screen. It wasn’t random static. It shifted.

“Could be current,” he said.

“At two miles down?”

He didn’t reply.

A flicker again — then nothing.

“I’m checking the observation chamber,” I said.

“Harper—”

But I was already walking. The chamber was silent except for the soft electric buzz of the monitors. The feed from the external cameras showed blackness. Infinite, patient blackness.

I leaned closer. My reflection hovered over the void, ghostly pale, lips slightly parted. Then something moved in the dark. Just a flash — a distortion. I flicked the floods on. The hull flared into visibility, silver-grey and sweating condensation. There — near the edge of the frame — a handprint. Pressed into the metal.

I froze.

The light shimmered, and then — faint, unmistakable — I heard it through the steel.

Knock. Knock. Knock.

“Reyes!”

He appeared a moment later, eyes wide.

“Listen,” I whispered.

The sound came again. Three soft blows echoing through the frame of the ship, each one sinking into my bones.

Reyes turned pale. “That’s impossible,” he said. “We’re two miles under.”

The Captain woke everyone. Ten of us gathered in the mess, jittery and whispering. Theories tumbled out — pressure shifts, hull expansion, sonar ghosts. But nobody could ignore that every one of us had heard it. Then Porter, our engineer, squinted at a monitor, asked us to zoom in, as if he knew he would see something we wouldn’t. The camera feed magnified a section of hull where something shimmered, pulsing faintly like heat mirage in the water.

“It’s moving,” he said.

The Captain ordered more light. The shimmer vanished. On the external microphone, a soft dragging sound scraped against the steel.

Knock. Knock. Knock.

I never thought I would live to see the day where a simple sound would frighten everyone of my fellow crew. I had seen every single one of them face danger, death, in the face before, without ever breaking a sweat. Yet none of us slept that night. The Odyssey felt different now— heavier, slower, as if the ocean had thickened around us. At 6:00AM, I found Porter sitting in the mess, shivering.

“You look like hell,” I said.

He raised his hand. Three red circles marred his palm.

“It knocked back,” he said.

“What?”

“When I was checking the air valves. From inside the pipes.”

My stomach twisted. “Inside?”

He nodded. “It’s in the sub.”

I laughed. I don’t know why, but I laughed. As if I was the butt of some stupid prank. As if I found myself discovering the joke, as if to say, “Oh you guys. You got me.”

The look Porter shot at me however snapped me out of my humorous daze.

“Maybe it was your echo?” I asked, trying to fill the silence that came after I stopped laughing.

“Maybe,” he replied, but I do not think either one of us were convinced by that theory.

Two men disappeared the next night. I have never felt so guilty about laughing. No alarms. No sign of a breach. Just gone — bunks empty, boots still by the door. Reyes found a puddle of saltwater near the aft chamber. No leak above it. Three shallow finger dents pressed into the floor.

The Captain assembled us again. “We’re surfacing,” he said.

But when we started the engines, nothing happened. The lights dimmed. Systems flickered. The red emergency glow returned, washing us all in blood. And from the bulkhead came the sound again.

Knock. Knock. Knock.

We tore through diagnostics. Porter’s scanner pinged an anomaly in the wall; a pulsing mass inside the steel. Then the wall itself began to bulge. At first it was subtle — a slow swell, like a lung filling. Then it warped outward with a metallic groan.

“Move!” I shouted.

The wall split open. No water poured through. Instead, a black vapor spilled out — viscous, shifting, threaded with faint veins of light. I saw a face in it. Or something that was trying to be one. A human outline pressing against the steel from within. It lifted its hand and tapped three times. Then a familiar sound rung in my ears. I could hear it laughing. A familiar laugh. The same laugh that I adopted from my Grandpa. I stumbled back as the automatic bulkhead slammed shut, sealing the section. The laughter became faint, and drifted off into silence.

Hours passed. The air felt wrong — charged, heavy, almost humid. The emergency lights flickered like candlelight. The Captain murmured a prayer over the console. Then the intercom crackled.

“Harper,” Porter’s voice whispered. “It’s talking to me.”

“Where are you?”

“In the storage bay. It says you shouldn’t have opened the lights.”

“Porter, listen to me. Don’t touch anything. Don’t open—”

He laughed softly. “You hear it too, don’t you? Three knocks. Always three.”

The line went dead. Then a deep metallic boom shook the ship.

Knock. Knock. Knock.

The sound came from everywhere — the hull, the vents, the floor under my boots. We ran to the storage bay. Water trickled out beneath the door. When we forced it open, Porter floated near the ceiling, eyes open, skin paper-white. Behind him was a shadow shaped like a man, its face stretched thin like fabric in a current. It pressed its hand against the wall.

Three knocks.

I sealed the door.

By morning, the Odyssey had gone quiet again. Half the crew missing. The Captain’s voice was steady but broken. “We’re surfacing manually.”

We worked the ballast pumps by hand. The walls creaked.

Reyes watched the sonar. “It’s following us,” he said.

“What is?”

“The thing. It’s right below us.”

He showed me the screen. Two blips. Ours — and something else, mirroring our ascent perfectly. As we rose, the sound returned.

Knock. Knock. Knock.

Louder now. Closer. The hull screamed in protest.

“Blow the tanks!” the Captain shouted.

We did. The sub lurched upward. For one brief, trembling moment, I felt hope. I could feel the salty air on my skin, the view of a sunny sky. I could imagine myself at the bar, with my friends, telling them this crazy story, of the strange being that found itself inside our sub. They’d laugh and call me a liar, until I told them of the crew we lost. I’d then pour a drink out for them, reminding myself of what I lost. My thoughts snapped back to reality when I heard it. The same laughter as before. My laugh. Then every light turned blue. The air grew colder, thick with moisture. And from every speaker and vent in the sub came a whisper, so quiet I almost mistook it for thought.

“Don’t open the door.”

The thought of being outside once more compelled me. I felt my hands reach for the door, as if they were being guided. I knocked three times and it opened. I saw light for the first time in months, but it was not the light of the sun. It was blue. It was beautiful. It washed over me and I felt a calmness. A euphoria of sorts. It reminded me of how I felt when my Grandpa would come and visit. The joy of seeing a loved one after you have missed them. The feeling of belonging, of home. I laughed with this joy in my heart as the water filled my lungs. I laughed as the blue light turned into darkness. I laughed as I let it in. I laughed as I knocked three times on the outside of the submarine.