Dr. Franklin sealed off the airlock as I strapped myself into the pilot seat of the Nautilus, beginning to test the various systems of the ship. He hummed a tune as we worked, one I had grown frustratingly accustomed to over the course of our working together. Loss to science be damned, if I had to hear him hum “The Irish Rover” one more time I would bash his head in with a wrench.

After the airlock was fully sealed and Dr. Franklin was strapped into the passenger seat I radioed in to Captain McDougal of the Avalon, whose deck the submarine was currently atop of. “Alright Captain”, I spoke into the microphone, “we’re all set. You can lower us into the water at your leisure. Over.”

There was a crackle from the speakers for a moment before Captain McDougal’s voice came through. “Roger that Dr. Schmidt, we’ll have you and Dr. Franklin in the water in just a moment. Over.”

Even through the thick hull of the Nautilus I could hear the whir of the crane as it slowly lifted up the submarine and began to rotate, moving us over the edge of the ship. There was a pause and then the crane began to lower the Nautilus into the water, before finally there was a loud clunk as it was released from the crane’s grasp.

The speakers crackled again. “Alright Dr. Schmidt, you’re free to begin your descent. You and Dr. Franklin stay safe down there! Over.”

“Thanks Captain. Over and out” I responded, before flipping a few switches and adjusting some knobs. A moment later and the Nautilus started to slowly sink down into the depths of the ocean. This area was relatively unexplored, so we didn’t have a great idea of what we’d find down there, but scans had indicated it was somewhere around 9500 meters deep. I estimated it would take a little over an hour and a half for our little submarine to reach the bottom.

The interior of the Nautilus was cramped, but not too unpleasant, with the two seats built for comfort in the event of long term missions. There was a single, extremely reinforced porthole to look through, but most visibility was via the camera installed on the exterior of the craft.

Bizarrely, the submarine did possess an extremely small airlock, barely enough for one person to squeeze through at a time, along with some scuba gear. This was justified in training as a method of escape in the event that the submarine was unable to fully reach the surface, but at the depths we were operating at it seemed utterly useless. Anyone who left the safety of the submarine at, say, 6000 meters, would leave behind a body that was completely unrecognizable even if it was successfully recovered.

As I pondered the ridiculousness of the airlock, Dr. Franklin began to hum “The Irish Rover” once again. “Will you stop that Robert? It’s getting on my nerves.”

He stopped humming and looked over at me sheepishly. “Sorry Amelia”, he said, “I just hum when I’m nervous is all.”

“There’s nothing to be nervous about”, I responded, perhaps a bit curtly, “or do you not trust my piloting skills by now?”

“It isn’t that. It’s just, don’t you ever feel scared? Going down this deep?” There was some slight tension in Dr. Franklin’s voice.

I sighed, rolling my eyes as I checked our depth gauge. “You know Robert, I swear you’ve got to be the only marine biologist in the world with thalassophobia.”

That got a chuckle out of him, and he gave a quiet “Maybe so” in response before leaning back and closing his eyes as he tried his best to relax. I felt a little bad for him, I can kinda understand his nervousness, and I understood he was going through some tough times at the moment. His mother was currently in the hospital on life support, nearing the end of her life. He’d been offered to sit this dive out, but he had refused, insisting that it was in the best interests of scientific advancement. I couldn’t help but wonder if it was just the crushing depths of the deep sea that was weighing on his mind.

As the Nautilus continued on and on into the deep, the light became fainter and fainter. The various schools of fish we passed began to become fewer and fewer, until soon it felt as if we were all alone in an endless, starless night. It was slightly eerie to be sure, even to a seasoned researcher like myself.

About fifteen minutes later, once we reached around a kilometer down, we found our first deep sea organism. Slowing our descent until we stopped moving, I moved the camera to focus in on the indistinct shape on the monitor, until it became clear. Floating, nearly motionless save for the occasional movement of its fins, an anglerfish hovered there in the blackness. Its lure faintly luminesced, and its beady eyes reflected back the glow from the Nautilus’s exterior lights. Dozens of sharp teeth stuck out of its half open mouth like a fistful of needles.

“Strange little bugger isn’t he” I remarked to Dr. Franklin, who nodded slightly.

“Indeed”, he replied, “It looks like a specimen of Melanocetus johnsonii to me. They have a fairly cosmopolitan distribution, so it’s not too surprising to find down here. Still, good that we have a record of it.”

Making a note of it in the ship’s log, I directed the Nautilus to once again continue its descent, leaving the anglerfish to its deep sea wandering. Thirty minutes later or thereabouts, I radioed in to the Avalon. “Captain McDougal? Over.

A moment of static, followed by a reply. “Yes Dr. Schmidt? What news from the briny depths? Over.”

“We are now about…” I double checked the depth gauge “five kilometers down, a little over halfway. So far nothing too interesting, but we’ve still got quite a way to go so I’ll keep the cameras rolling. How’s the weather up there captain? Over.”

“It looks like a little bit of rain is coming in Dr. Schmidt, but nothing I’d be too worried about. What’s it like down there? Over.”

I peered out of the porthole into the all consuming blackness of the water. It seemed to go on forever. “Dark and gloomy Captain. I’ll radio in once we reach the bottom. Over and out.”

I noticed Dr. Franklin had been quiet for a while, so I gently tapped him on the shoulder. “You alright over there Robert?”

He looked up at me, seeming almost as if he had just woken up from a dream. “Huh? What? Oh, yes, I’m fine Amelia, just thinking.” He seemed troubled, more nervous than normal.

I looked over at him for a moment, glancing at the bags under his eyes. “You haven’t gotten much sleep, have you Robert? Something bothering you? You want to talk about it?”

“I’m fine, really Amelia.” His face betrayed his words however.

“C’mon Robert, we’ve known each other for what, twelve years? I know you’re stressed out about your mother, there’s no shame in that. You can talk about it you know. What’s said 5000 meters below the surface stays 5000 meters below the surface.”

Dr. Franklin laughed a little, seeming relieved. “I won’t lie, I am worried about her. I know it’s her time soon, but knowledge doesn’t make acceptance any easier. I keep thinking about the little things about her, you know? Things like how she laughs at stupid puns, how she always knocks on the door to the tune of ‘shave and a haircut’, things like that. Being alone in the darkness in this tiny submarine makes it all a bit harder to ignore. I’ll feel much better once we reach the bottom and I can make myself useful.”

“I can understand that”, I replied, gazing at the monitor which displayed nothing but blackness, “when my dad passed away a couple years back I kept making myself stay busy, I refused to be alone with my thoughts. Eventually I found myself on a plane flight, only to realize that in my haste I’d completely forgotten to unpack my laptop, phone, or even a damn book from my luggage. I sat through the whole flight with only my thoughts to comfort me and I’ll admit it, I cried a lot. But by the time I landed, I felt better. It’s important sometimes to let yourself think about those things.”

Dr. Franklin nodded, but stayed silent. I noticed a tear in the corner of his eye, but didn’t mention it. I just kept focusing on the controls, the monitor, and the porthole. I found myself losing track of time as we descended, just staring out into the vastness of the ocean. Even in a trench like this one and behind inches of steel I still felt exposed. It didn’t help that I could barely see a damn thing, just the occasional drift of marine snow (a glorified term for bits of fish feces and other biological detritus) and the impenetrable blackness of the deep sea. Every so often we’d encounter some sort of fish or other animal and I’d make a note of it in the log, before I once again set the controls to continue downwards.

I barely even processed when Dr. Franklin continued his humming of “The Irish Rover”, I was entirely too focused on the gloom. If anything I welcomed the tune at this point, it was more soothing than the faint creaking of the submarine’s hull as it adjusted to the pressure and the whir of the air processor.

After what felt like eons we reached the bottom of the trench, the depth gauge reading at 9487 as the Nautilus gently set down in the pelagic ooze. Finally allowing myself to relax a bit, I swiveled the camera around to give us a better look at our surroundings. Not much around, just rocks and slime, though I did notice a sea cucumber feeding off of some of the detritus.

As I adjusted my seat slightly and stretched a bit, Dr. Franklin sat up in his chair, pointing at the monitor. “Did you see that?” he asked, voice slightly excited.

“See what? The sea cucumber? What, is it some sort of rare species or something?” I asked, my back popping as I groaned.

“No, not the sea cucumber, something else. Something bigger. I don’t know, I only caught a glimpse of it for a moment before it moved out of sight. We should head after it, it could be a new species!” He sounded excited, a welcome change from his nervousness during the descent, so I obliged his request.

Raising up the Nautilus from the ooze, I set us moving forward slowly in the direction he had indicated.

The exterior lights swept gently over the ocean floor as we were quietly propelled forward by the submarine’s engines. Occasionally I would see something loom out of the gloomy nothingness, only to realize it was just only a rock. I was beginning to get impatient after about five minutes of this whilst Dr. Franklin continued his incessant humming.

“Look Robert, I’m not seeing anything, are you sure the stress just isn’t getting to you? Maybe it was just a trick of the light” I said softly, trying not to offend him.

“No, I saw something dammit, I don’t know what but it was real, not a stress-induced hallucination or a brief moment of pareidolia!” Despite my best efforts, Dr. Franklin was getting upset, even angry.

“Alright, fine, so you saw something. Can you tell me what it looked like?” I replied, trying to calm him down. I glanced over the monitors, trying to get a glimpse of something, anything that might have aroused Dr. Franklin’s curiosity.

“I don’t know quite how to describe it, I didn’t get a great look at it” he said, bouncing his leg in a combination of excitement and frustration. “From what little I could see it was dark in coloration, perhaps slightly reddish, and large, huge even. I think I may have caught a glimpse of a fin perhaps. It moved out of sight right after we hit the bottom, maybe we disturbed it.”

I looked over at Dr. Franklin in alarm. “Huge? Robert, how huge are we talking here? Great white shark, sperm whale, megalodon, what?”

He shook his head, eyes still focused intently on the monitor. “I don’t know exactly, like I said I didn’t get a good look at it, only catching a glimpse of what might have been the tail end, but from that brief glance it has to be at least 12 feet long.”

I stopped the submarine then, setting us down in the ooze once more as I turned to face my colleague. “At least!?” I was practically yelling. “Robert, I don’t know if you’ve noticed, but the Nautilus isn’t a damned battleship. We’ve got a thick steel hull yes, but it’s not like this thing is built to stand up to Moby Dick. If we run into some kind of deep sea predator and it decides we’re prey, we could lose some valuable equipment.”

Dr. Franklin almost yelled back at me, but his counterargument died on his lips as he stared out the porthole. “Oh my God” was all he had time to say before everything went to Hell.

There was a loud groan of metal as something crashed into the side of the Nautilus, alarms blaring as the cameras and exterior lights were smashed. Fortunately I was well strapped in, otherwise I hesitate to wonder what may have happened. The tiny submarine tipped end over end as something huge continuously smashed into it, and all the while I cursed up a storm. After a minute or so the buffeting stopped and the Nautilus sank down into the ooze once again.

“Robert, are you alright?” I asked, dazed and feeling a bit nauseous from motion sickness.

“I’m okay” was his timid, quiet reply. I had been swearing like a sailor throughout the entire ordeal, but Dr. Franklin was entirely silent save for a few grunts of pain and discomfort. I looked over at him and saw him staring wide eyed at the pitch blackness through the porthole. The lights had all been destroyed, so it was impossible to see anything, the window may as well have been a black circle painted on the wall.

“Did you see what hit us? What was that thing?” I questioned him frantically, trying to figure out what our next course of action should be. Dr. Franklin didn’t reply, he just kept staring at the porthole, beginning to hum “The Irish Rover” faintly. I checked the control panel, noticing red flashing text which spelled out the words “propellers offline”.

Praying that the radio still worked, I attempted to reach the Avalon. “Mayday, mayday, the Nautilus’s propulsion system is damaged, along with the cameras and exterior lights. We’re going to need to be pulled up, over.”

There was a painfully long moment of static. It only could have lasted a few seconds but it felt like minutes as I waited horrified that we could be cut off. Luckily, however, Captain McDougal answered.

“Roger that Dr. Schmidt, we’ve got your coordinates fixed in the system, looks like the tracking device is still operational. We should have you up here in about two and a half hours, depending on how fast we can get the cable down there. Hang tight, over and out.”

I let out a breath I hadn’t realized I was holding, sighing in relief. I closed my eyes and tried to relax, but Dr. Franklin’s maddening humming was getting to me. I looked up and was about to tell him to shut it, when the humming stopped suddenly. Dr. Franklin’s face was pressed against the porthole, staring through it. His whole body was stiff as a board, entirely still, all of his attention focused on that tiny circular window.

Happy that he was finally quiet at least, I leaned back in my seat, trying to rest a bit. I was managing to stay fairly calm given the circumstances. Fifteen minutes or so went by like that, with Dr. Franklin staring out the porthole while I just sat in silence. I was even starting to doze off if I’m being honest, after the intense adrenaline rush wore off, I had become incredibly tired. My short nap was interrupted suddenly when Captain McDougal’s voice came in over the radio once again.

“Nautilus, this is Captain McDougal. That rain I told you not to worry about? It looks like it's turned into a bit of a storm. It’s not safe for the Avalon to stick around at the moment. I’m going to take her out to quieter waters for a few hours, but we haven’t forgotten about you. You should have enough supplies and power to remain down there for a couple days if you need to, but it's not going to come to that, I promise. We’ll get you out as soon as we can. Hold tight down there Amelia. Over and out.”

I slammed my fist on the dashboard in anger. “Goddamn it!” I shouted, loud enough to ring in my ears due to the cramped space. Dr. Franklin shushed me, putting a finger to his lips.

“Be quiet. You’ll scare her off again” he said, sounding almost excited.

“Scare who off?” I asked, getting a bit nervous. I didn’t want to be down here with someone having a mental breakdown. Dr. Franklin motioned for me to look through the porthole, and so I did, leaning forward to get a better view.

At first I didn’t see anything. With the exterior lights broken all was blackness once again. However, as my eyes adjusted slightly I detected a faint luminescence in the distance, an indistinct shape. I couldn’t quite discern how far away it was, so I wasn’t able to tell its exact size, but it seemed to be eerily anthropoid in outline, though at the time I was sure it was just a case of pareidolia. “What is that?” I muttered, more to myself than to Dr. Franklin.

“Can’t you tell?” he whispered, almost sounding reverent in his tone, “She’s my mother!”

I kept staring at the distant, glowing figure, trying to make out further details, but I couldn’t make out more than a vague shape. Eventually, Dr. Franklin gently tapped me on the shoulder saying “May I look again please?” in an unsettlingly calm voice.

Despite his apparent calmness, looking into his eyes I could see an incredible amount of tension, like a violin string pulled so tightly it is about to snap. I knew if I were to deny his request, he would get violent.

I pulled away, trying to make myself comfortable in my seat. A million questions swam in my brain, and I began to lose focus on my surroundings as I pondered all that was going on. What was that thing out there? Why does it look humanoid? Why was Dr. Franklin convinced it was his mother?

As I continued thinking over my situation, I tired myself out yet again, and before I knew it I must have fallen asleep a second time. I know, it doesn’t make any sense under the circumstances, but you must understand I didn’t think I was in any immediate danger, and it’s not like there was much else to do.

I awoke to the sound of knocking on the hull. I could tell it wasn’t coming from inside the submarine, it was too loud, like the toll of a bell. It was the old “shave and a haircut” knock, plain as day, too distinctive to have been a coincidental sound of the steel hull adjusting to the pressure. I shot up in my seat. Dr. Franklin was staring upwards, reverence on his face.

“Mother?” he whispered, tears forming in his eyes.

I moved over to the porthole, pressing my face against it, but I saw no sign of the glowing entity from before. Again the knocking sounded against the hull, slightly louder this time, and the exact same pattern. Dr. Franklin clambered towards the airlock, hands shaking.

“Don’t!” I shouted, reaching a hand towards him. Without a word, he swung his fist directly at my face, smashing my glasses and making my vision go black for a moment. When I came to a few moments later, Dr. Franklin was already in the airlock chamber.

“Don’t do it Robert!” I screamed, desperately trying to crawl over to him, but the tight confines of the Nautilus, combined with my splitting headache and lack of glasses, made movement difficult.

“Goodbye Amelia” he said, smiling as he pressed a button. The airlock door closed on my end, and I began to shriek incoherently, pounding my hands against it. I am grateful the airlock had no window to look inside the chamber, I don’t think my mind could have handled watching Dr. Franklin die from the sudden pressure change.

I collapsed on the floor, sobbing. I considered calling in to the Avalon for help, but I knew that the only thing they could offer in terms of assistance were words of comfort. I just kept laying there, curled up in the fetal position for several minutes, unable to process what had happened.

Then I heard it.

The distinctive tune of “The Irish Rover”, played in knocks on the outer hull of the Nautilus.

I looked out in the porthole in confusion, but I saw nothing. My vision was too blurry to see much of anything even if it wasn’t pitch black out there. The tune continued incessantly, getting louder and louder as it progressed.

“Stop it!” I cried, plugging my fingers into my ears in vain. The knocking just kept growing louder and louder, ringing in my ears which only added to the hellish cacophony. I began to just shriek, screaming my lungs out in a desperate attempt to block out the never ending, agonizing sound.

They say I was still screaming when they pulled me out after the storm passed. That I kept shrieking until they gave me sedatives.

It’s been a few weeks now, and I haven’t been back to work since. I used to love the ocean. I thought it was beautiful, mysterious, and fantastic. Now I can’t even go into an aquarium without having a meltdown.

I don’t know what was down there. I don’t think it was the ghost of Dr. Franklin’s mother, she died a few weeks after my experience. I don’t think whatever was knocking to the tune of “The Irish Rover” was the departed spirit of Dr. Franklin either.

The anglerfish lures in its prey with a highly specialized fin, one that glows slightly in order to be more attractive to other fish. When they get close enough, the anglerfish lunges, devouring them. That glowing figure in the distance, it makes me wonder whether or not Dr. Franklin fell victim to something quite similar.

But that doesn’t explain the knocking. It doesn’t explain how it knew that his mother always knocked to the tune of “shave and a haircut”. It doesn’t explain how it knew Dr. Franklin’s irritating habit of humming “The Irish Rover”. Did it pluck those sounds out of our brains to try and lure us outside? Am I just insane?

I requested to view the video recording of our descent, but the higher ups won’t let me. They insist that the recording was corrupted, and that it’s unviewable. But I know the truth. In the last few seconds of their operation, the cameras must have caught a glimpse of that thing before it smashed them. They don’t want the public to know about it, to cause mass panic at the knowledge that something that terrible could exist on this planet.

I remember the legends of mermaids, inhuman creatures luring sailors into the waters to their deaths by pretending to be human beings. I also remember that deep sea creatures often come up to the surface when it gets dark in order to find food. If you ever find yourself sailing at night, and see or hear something that seems human floating in the water, ignore it. Go below deck and pray it goes away. I don’t care if it talks to you, sings to you, begs for you to come help it. Just leave it alone, unless you want to go to a watery grave.