I'd heard about the secret beach from some Thai fishermen and had my heart set on studying the unique ecosystem, but the rest of my group said the idea had ‘dumb foreigners get themselves killed by acting like dumb foreigners’ written all over it.

Then later on that night, at some dive bar, Johnny waited until our girlfriends nipped to the bathroom and told me he was in. He even promised he’d talk the ladies round, so long as I helped him with a special surprise.

Three months of travelling together had taught me that guy could get anything he wanted with a quick flash of that movie star grin...

He waited until Alex and Vicky got drunk on fishbowl cocktails before saying, “I think it sounds like fun, while Gary’s off creaming over fish the rest of us will have the place to ourselves. We can rent a little boat and set off before sunrise. I’ll leave a note telling the hotel staff to send help if we’re not back by supper.”

“I’m in,” Alex said, snuggling into Johnny’s muscular arm.

Vicky pursed her lips. She and Alex had been best friends since childhood and looked so alike—short with blonde hair and bright smiles—locals frequently mistook them for sisters.

“Fine,” she said.

First thing in the morning we set off cutting through waves, Johnny at the helm. The sun stayed hot on our backs, and sickening fumes from the boat’s engine mixed with the salty ocean air.

Did you know Thailand has almost 3,000 miles of coastline? That’s a lot of ocean for hungover tourists to get themselves lost in.

But, again and again, our fearless skipper insisted he knew the way.

Close to noon, long after we should have arrived, he called, “Land ho!” then everybody’s head whipped toward a dark spec along the cerulean horizon.

A giant sea stack, at least three hundred feet tall, rolled toward us. I let out a quiet groan, secretly annoyed macho man found the place through sheer dumb luck.

It took fifteen minutes for him to steer us toward a tunnel along the Southern side where he killed the motor and let the boat bob up and down.

“Finally,” said Alex, as she grabbed flippers and snorkels from beneath the stern.

While Johnny wrestled a strap around his heel, he leaned in close to me and whispered, “Got everything ready?”

I tapped the waterproof bag hanging around my neck.

He shot me a thumbs up before tipping backward, overboard. Everyone else climbed down the ladder, me last, into the blissfully warm water.

Beside the mouth of the tunnel, Vicky floated in place, anxious.

“What’s the matter, afraid of the dark?” Johnny called back.

“More like afraid of barracudas.”

“There’s no barracudas around here,” I said, swimming alongside her. The ocean was so clear you could see for miles around. “Come to think of it, I don’t see any fish.”

Johnny said, “Give it a rest Aquaman,” then flicked on his headlamp and vanished into the shadows. He pulled that ‘alpha male’ bullshit a lot.

My hand laced with Vicky’s. “Don’t worry, if any barracudas try taking a bite out of you, I’ll use myself as bait.”

Guided only by our headlamps, the four of us swam along, the narrow trail widening further into the bowels of the stack.

"These walls are freaky," Alex said at one point. "I think there’s bugs crawling over them."

After navigating a series of bends, blinding sunlight appeared before us. The tunnel opened onto a wide body of water, half the width of an Olympic swimming pool and probably fifty foot deep. A horseshoe-shaped beach encroached on three sides, outlined by a narrow forest lush with vegetation and palm trees. Everywhere you looked, there were vibrant hues of gold, turquoise, and emerald, all silhouetted against the grey-black rock walls encasing the enclosure, giving the space this secluded, intimate feel.

“Was I right or was I right?” Johnny yelled as he swam past the ‘bowl’ and up onto the sand. “Paradise.”

You couldn’t argue there. Hell, it's why I suggested the trip in the first place…

After kicking off his flippers, he helped Vicky up onto dry land. I felt a pang of jealousy watching them smile at one another.

The three of us spread out and explored while Alex floated aimlessly. The trees provided shade from the constant heat while gentle waves crashed against rocks, producing a soft melody that could lull babies to sleep. There was no wildlife—not even a marine gastropod—which seemed odd, however the uniquely shaped flora intrigued me.

After awhile, I noticed Johnny waving for my attention at the far edge of the beach.

Shit, I’d almost forgotten. I grabbed the phone from my neck bag, opened the camera app, and gave him a nod.

He reached into his shorts pocket, spun around, and discovered a lifeless basin.

“Alex?” he called out.

Vicky stepped out from behind a fern. Johnny ran up to her and said, “Is Alex with you?”

She looked from him to me and shook her head. I slipped my phone back into the pouch, then

all three of us spread about, searching and calling for Alex. In under a minute, we completed a full lap of the forest.

“Maybe she went back to the boat?” Vicky offered.

“She wouldn’t go without telling us,” Johnny replied, his voice wrought with concern.

Just then, a gurgle went up; the sound of a clogged toilet with fishbones lodged in its throat. Altogether, we spun toward the water, and as we did, a wave crashed over the beach, nudging our discarded flippers.

There were more gurgles, real guttural, then a ripple spread out in every direction from the centre of the bowl. It looked like a 500lb canonball had plummeted from the top of the stack. The resulting wave briefly engulfed our ankles and dragged the flippers away.

Johnny shouted, “Alex?” His voice echoed off the enclosure, back at us. Vicky grabbed my arm, her pulse gathering speed.

That horrible cycle continued: gargle, wave, gargle, wave. This was no rhythm of nature, more like a beach gagging.

“Gary, what’s going on?” Vicky asked. Even though I specialized in marine biology, the group looked to me for answers about any kind of natural phenomena, then chastised me if I didn’t know the answer.

The next wave vomited strange, blue-white sausages onto the sand. I thought they might have been a trail of seaweed until I nudged one with my toe and felt something rubbery.

“Oh shit,” I said, flinching away.

It was a rope of intestines, threaded with veins. At the realization, a hush fell over the group.

My eyes travelled toward the centre of the basin, where a red mist spread through the clear turquoise, diluting like squid ink. Blood.

Vicky retreated, stammering, while Johnny looked between me and the discarded intestine for nearly twenty seconds. “What the fuck is going on?”

The speed of those waves accelerated, cascading, one after the other, and quickly dragged the pale snake away.

A study flashed through my mind: one about dolphins launching themselves onto mud banks to create bow waves which maroon fish. This spark of a suspicion spurred me to say, “Get onto the rocks, there’s something in the water.”

The two of them exchanged a look, another pang of jealousy stabbing me in the ribs. “Now,” I shouted, louder than intended.

The rocks were slippery with moss. While Vicky and I hopped past vines and the top halves of a palm tree in a deadly game of ‘the floor is lava’, Johnny stood with his head in his hands, internally debating while the water surged high enough to swallow his thighs.

With reluctance, he eventually hopped after us.

Meanwhile, those gruesome gurgles rang out, louder each time.

Toward the back of the enclosure, boulders lay spread about connected with the base of the rock wall. No sooner had we reached the edge when the strongest wave yet broke against the chest-high rock we’d all halted on and launched a hissing column of foam into the air.

Now only a few metres of shrinking beach remained. The ocean had come to meet us.

“We have to climb,” I said, breathless.

Johnny grabbed my shoulder before I could find a suitable starting point, spun me around, and pinned me against the wall.

“What the fuck is going on?” he shouted. “What the fuck happened to Alex?”

“Those waves are gonna sweep us off this rock,” I stammered.

As if on cue, salty foam splashed over all three of us.

“See? We’re being…hunted.” I said, feeling ridiculous for even uttering the word. None of this was clear in my mind.

“Gary, what the fuck is going on?” a frantic Vicky asked from behind my assailant’s shoulder.

“Something hunted Alex?” he said, like it was my fault, pinning me even tighter.

“Yes…no…I don’t know.”

“What do you mean you don’t know? You're supposed to be the fucking brainbox."

“We have to climb,” I said, my hysteria mounting. "There's something in the water."

His right hand curled into a fist, but before the strike landed Vicky grabbed his forearm and shook her head. She was trembling all over.

Johnny released me, begrudgingly.

I felt around for divots and recesses—areas easy to traverse. My fingers were still wet, which meant I slipped again and again, and for a moment I had some sense of how spiders must feel trapped inside a bathtub.

Roughly eight feet up, I came across a portion of wall which had a cavity deep enough to lay flat along my stomach and reach down for Vicky.

By now the beach had been devoured; only the caps of palm trees poked out, bowing under every wave.

Following me up Vicky’s foot slipped once, twice.

“Come on, come on,” I shouted.

Ever the hero, Johnny, now gone up to his ankles, cupped his hands and boosted Vicky like a weightlifter performing a clean and jerk, raising her high enough she could be hoisted onto the shelf alongside me.

He raced up the wall after her, his fingertips nudging mine, briefly. I was stretching as far as I could, honest.

But then the most powerful wave yet crashed into the wall. I lost sight of Johnny in the resulting spray.

He resurfaced twenty feet ahead, already paddling in our direction, and at that exact moment, the repetitive gurgle transformed into a churn like somebody yanked out a plug, then the water swirled in rich, inward spirals. Immediately the bowl became a whirlpool.

My suspicions were correct: we were being hunted. But by what? What sort of creature manipulated the water like that?

Within seconds the beach emerged, reasserting itself. On the shelf, I pulled Vicky to her feet, and then we stood there, transfixed, while Johnny careened around a central point, closer to the middle of the basin area.

His arms flailed as he screamed and got sucked toward the bottom of the vortex, fifty feet deep.

And that’s when I saw…it.

Visible through the clear waves—but also a considerable distance away—what looked like a black serpent wrapped around Johnny’s ankle, worming its way up his body. I grabbed the phone from my neck pouch and zoomed in.

Huddled close to me, Vicky pointed at the screen and said, “What the fuck is that?”

It wasn’t a serpent. For a moment I thought it might be a giant tentacle, but then it split apart into five segments which tapered off to the thickness of a severed arm, each dark on the outside, fleshy and pink on the inside, covered with rows of suckers, moving, twitching, writhing, like hundreds of hungry, hungry mouths. Wherever they eagerly latched on skin tore off in fat clumps.

Red mist spread about the water as our companion got reeled down like a fish on a line, the appendage flexing like a working oesophagus. More and more water poured in through the tunnel we’d arrived by.

As our friend plunged deeper and deeper, a gaping pit the diameter of a manhole cover shivered open directly beneath the tentacle. I zoomed in on that area, a horrible realization sliding up my spine. Luminous blue lights and barbed fangs lined the inside of the hole.

It was a mouth.

As the tentacle-tongue reeled Johnny inside, the mouth closed with enough force to crush his ankles together, like the point at the end of a pencil.

A trail of bubbles spewed from the poor bastard’s mouth, which meant he hadn’t died yet, and even had some oxygen left in those lungs.

Above him, the water level evened off, perfectly calm. Vicky buried her head in my chest, sobbing.

The process of digestion took several minutes, and so far as I could tell Johnny didn't die until he was disappeared up to his waist.

Once he vanished, the stack quivered and shook. I felt the intense vibrations through the soles of my feet.

Another gurgle went up, the beach whirled and foamed again, then bones with gristle still attached floated to the surface.

Leftovers.

Vicky stopped sobbing long enough to say, “What the hell was that thing?”

“A mouth,” I said, emotionless. “When Johnny got too close to the centre, a tongue slid out. Like a Bobbitt worm.”

On the verge of a complete breakdown, she said, “You mean there’s some sort of killer worm down there?”

The walls trembled with furious convulsions, like an expanding lung. I shook my head. “It’s no worm.”

“Please start making sense.”

By now those circles of waves and ripples had gone up again, turning the pool beneath us into a minefield. Mercifully, there seemed to be a limit to how high the water could rise. We were safe. For now. “Look, the waters violent again, see? And the walls, they’re kind of…shivery, right?”

She nodded.

“I think this whole stack is resting on something big. Think about it, the water level adjusted to capture Johnny. That suggests a level of intelligence. This sea stack, I think there’s a creature beneath it. One big enough to make the entire structure shudder.”

“So, what, it hunts by gulping down water?”

“Possibly. It’s just a theory.”

“Can you call for help?” she pointed at my phone.

I tried. “No.”

“So what do we do?”

Dropping into the water would be like diving headfirst into a meat grinder, so that was out. I glanced up at the top of the structure. Professional climbers wouldn’t risk an ascent that treacherous: a 250ft journey to the top, with one small slip meaning a plunge straight into the drink. Best case scenario, you'd crack your skull against an awkward rock and bleed out before getting slowly, painfully digested…

Just then, the realization hit me. “We could have escaped while the creature swallowed Johnny,” I said. “This thing’s mouth closes to eat, which temporarily calmed the water. We missed our chance.”

“Should we wait for the hotel staff to find us?”

“They won’t realize we’re missing until dark. Then you have to factor in how long it takes them to find the boat, assuming they actually find it. Plus, we’ve got no food or water.”

I contemplated for a moment. You could tell from the way the bowl churned the creature understood more prey lurked close by.

“I think we should get closer to the tunnel,” I said, finally. “It’s the only way in or out, we can shuffle along this shelf, look, it almost stretches the entire way.”

In the twenty minutes convincing her took, I found myself wishing I had half of Johnny's charm.

Most of the journey was a careful sideward shuffle along an upward slope, our backs flat against the wall, but at one point we had to spring over this little gap, and Vicky took her time working up the nerve.

At the exact moment she leaped across, the stack trembled, which made her foot slip. My hand shot out around her waist and pulled her in close at the very last second.

The timing couldn’t have been coincidental—this creature knew where we were and what we were doing. It thought tactically. That unsettled me.

Toward the edge of the shelf, two full bodies length away from the tunnel and twenty foot above the water, I looked straight down and said, “The creature can feel us.”

Vicky stared at me with sunburned eyes, confused.

“The walls trembled at the exact right moment. Maybe it detects movement along the stack, like a spiderweb.”

We stood until our legs ached then sat, the sun bearing down hot on our chests.

I made a mental note of everything I’d surmised about the creature.

Our biggest threat was the fact it displayed a level of intelligence, or at least reacted to certain stimuli. And with Johnny, that reaction had been instant. No way we could swim through the tunnel before the creature responded.

If it set ‘traps’ by manipulating the reservoir and walls, then what did that make the beach? A cancerous growth? Or perhaps a lure?

Once again, my thoughts drifted back to that missed window of opportunity…

At dusk, the darkened waves almost glittered. A briny aroma wafted out while we sat there, Vicky to my right, her head resting on my shoulder.

My arms became overcooked slabs of beef, my mouth dry from the thirst. Neither of us would last much longer. Hell, in another few hours swimming back to the boat would be harder than doggy paddling across the English Channel.

“Why did Johnny want to see this stupid place anyway?” Vicky asked.

“He wanted to propose.”

She looked up at me, shocked. “What?”

“He was gonna propose to Alex. He bought an engagement ring and asked me to take a video. He wanted it to be romantic and thought this would be the perfect spot.”

“Idiot,” she muttered.

I sat there, contemplating my next statement carefully. What had I to loose? “Not too much of an idiot to make out with though, huh?”

“What?”

“Two weeks ago,” I said, my eyes fixed on the shimmering waves. “That nightclub in Bangkok. I nipped away for a piss and when I came back, you and Johnny were…were…” My voice trailed off there.

The realization slowly spread across her face. “Our lives are in danger, Gary. Is a stupid drunken mistake really so fucking important right now?”

“A drunken mistake? You two were going at it like horny teens”

At that moment, I felt more embarrassed than anything. I should have confronted them that night, or at least told Alex, but flights had already been booked, deposits paid.

If I’d only had more balls, none of us would have wound up in this mess…

“Okay Gary, it happened.” She pushed away from me and stood. I did too. “I had a lapse of judgement, and I’m sorry. Now that’s out of the way, how the fuck do we get off this stupid fucking beach that you were so obsessed with?”

“A lapse of judgement? You think I haven’t noticed the stolen glances? You always said Alex could have done better, did you really mean Johnny?”

The two of us stared each other down, a showdown. Twitchy. Paranoid. We both wished for the same thing—that the other would mercilessly slip off this damned rock and into the drink. A dark part of me wanted to push her myself.

Then, as if on cue, the wall jerked with such force my teeth chattered together. Had the creature sensed the tension between us? Or was it simply inconvenient timing?

Either way, Vicky lost her footing and slowly slid along the shelf, her thin arms windmilling around, searching for something, anything, to latch onto. She screamed as she toppled over the edge.

A heroic dive forward by yours truly saved her at the very last second. I lay flat along my chest, our hands clasped, her trailing in mid-air, alternating between screaming and begging me not to let go.

If I simply relaxed my grip, the creature would have rang the dinner bell. Was it really such a horrible idea? She, like Johnny and Alex, would already be minced meat if not for my quick thinking.

But I couldn’t bring myself to do it. Despite everything, I still loved her dearly.

However, before I could haul her up, the wall trembled again. The powerful vibrations did enough to force her hand and mine apart, sending her plummeting into the perilous waters below.

I rose, heart racing, as she disappeared beneath the surface. By the time she re-emerged the bowl was already alive with foam and spit and cascading waves.

In the dim light, the inside of the mouth lit up like a glowstick, that ‘tongue’ sliding out from the hole once again.

As the water whirled toward the depths, Vicky got swept away. She slid toward the pit headfirst, trapped in the whirlpool.

The tongue completely enveloped her skull. Within seconds her top half had become flayed and unrecognizable from the sucker-pads tearing away flesh in fat globs.

Those skinny legs of hers did not stop kicking.

A dark part of my mind pondered whether it would be better to go feet first, like my loving girlfriend, or headfirst, like her secret lover.

I became so lost in thought I didn’t notice the water level had already settled. By the time I was staring at nothing more than the soles of two bare feet, I had the realization it may already be too late.

Amped up on fear and adrenaline, I took a little shuffle forward, became completely weightless for a moment, and then the water came up to meet me.

I put everything I had into swimming toward safety. Gaining traction was a struggle; every few strokes the current grabbed hold of me and held on tight.

I swam through the darkness, relieved my hypothesis proved correct.

But then, a powerful drag, like someone started slurping the ocean up through a straw.

Main course over, time for dessert…

I kept kicking. The walls slithered each time I touched them, a heartbeat. What did Alex say earlier: that they looked freaky? Oh fuck, I hadn’t escaped—I was still inside the creature. It didn’t inhabit the stack; it was the stack. Perhaps I was swimming through an intestine, or the throat.

Only vaguely aware of my destination I kicked madly while, around me, walls shifted and shivered. No face, no eyes, but a simple sentience which made me tremble.

A circle of moonlight drifted into view roughly fifty feet ahead. While I put everything I had into paddling, the water climbed higher and higher, hurling me from one wall into another. I became cut and bruised in a dozen places.

Soon I could see the silhouette of the boat, but my rescue vessel drifted further and further away. No, not drifting—the creature was shrinking the tunnel, cutting off the exit. This leviathan had a biology unlike anything else on earth.

As the cavern sealed itself shut, a huge wave of water careened toward me, one final obstacle. For a moment I contemplated holding my breath until I lost consciousness and drowned, rather than be served up fresh.

Pushing these thoughts away, I dove beneath the wave and launched myself forward like a torpedo, and once I reached a point where I couldn’t hold my breath a second longer, I came up for air, outside the stack.

Behind me, the tunnel had puckered shut.

Up ahead, the boat bobbed up and down, unconcerned by the day’s events. Quickly I swam around the side, hauled myself up the ladder, and flopped over onto the deck, exhausted.

Four of us set off that morning. And I hope now I’ve told you exactly what happened, you’ll understand that I am in no way responsible for the others deaths.

And why their bodies will never be recovered…