From Redditor u/Cannotakema:

Fresh out of college I got a job “In Cambridge, Massachusetts” or so they said… as an architect designing… whatever.

Ended up [working on] oil rigs. One beautiful morning, there were sharks going under the main platform like always, but there were two dead sharks. Next morning, three dead newly dead sharks, then four the next day. Then a steady four or five a day for a week or two…

[The dead sharks] would float up under the see-through deck that looked much like a metal colander. Crew would have to punch them down so the current could catch them with a large pole.

What made it really weird was they looked like they had heart attacks or died in their sleep, no marks or bites or anything. The guys on the rig had all kinds of theories. Then one morning while in a room that was completely submerged and had a beautiful view as we sat in a meeting.. .everyone got to see the reason the sharks were dying, like viewing it on a movie screen.

This octopus had made itself a home between the base and the deck. A shark was swimming by in a cruising fashion and we see these tentacles grab it right in front of the glass and snap it like a glowstick.

The marine biologist smiled and said, “Octopus is literally doing that to entertain themselves… like because he can.” The marine biologist lowered a dive camera and this octopus was HUGE.

The crew would joke about it thereafter, people would smoke on the deck at night, and people would say don’t let the octopus in. Seeing those tentacles was just insane for their length and to think about how a shark is mostly muscle and the octopus would just snap ’em.

It was scary.

From Redditor u/Mange-Tout:

I was sailing a small Sunfish around an island near Florida in shallow water. As I cruised along suddenly a large section of water directly in front of my bow exploded with a large splash. Immediately afterward my boat rammed into something under the surface and came to a complete stop.

My first thought was, “I’ve hit a reef,” but suddenly the entire boat was lifted up and spun around 90 degrees, almost dumping me into the water. Then there was another big splash and I saw something zoom away, leaving a wake behind it.

I was left freaked out and shaking. Then I thought to myself, “I must have hit a big dolphin. Maybe it was a manatee? Lots of dolphins around here…”

So, I finished my sail and went home. When I got to the beach I pulled up the centerboard and found a real surprise! A 2-inch chunk had been bitten out of the wood. You could clearly see the marks of three large teeth.

I’m very happy that I didn’t fall out of the boat that day.

From Redditor u/bidet_enthusiast:

Giant spears plunging in and out of the sea.

In the Gulf of Alaska, I have seen some sh*t. But one of the most terror-inspiring things I’ve seen are what can happen with some of the loose logs from the logging trade.

Sometimes when a big log gets loose from a raft, it becomes partially waterlogged and floats small end up. So you have this 4-foot-diameter telephone pole in the sea, sticking up 40 feet into the air. No biggie. Shows up on radar, and easy to spot.

Now, give that pole 20 years of floating around or so. It rots in such a way that it becomes sharpened to a perfect point by wind and waves, and looks quite menacing.

Now, put it in a gale with 25-foot waves (50-feet trough to peak)

…. And it becomes a towering spike of death that shoots up from the sea every 15 to 20 minutes, out of nowhere, 60 feet into the air, only to plunge down into the dark depths waiting to skewer some unsuspecting boat in a few minutes when it thrusts out of the ocean again.

It is a genuinely terrifying sight, rare, but not so rare that I haven’t seen two in one season. It’s like the spiked d*ck of Neptune looking for an opportunity to f**k your sh*t up in a particularly terrifying way.

From Redditor u/MadameMonk:

My dad was competing in a marlin fishing comp near Weepa (the pointy top bit of Australia). Battled a fish for four hours (they catch and release). As it neared the boat, crew readied to haul it onboard and a camera team went in for the tight shot, hanging right over the edge.

The marlin breached the water when a huge great white shark breached under it. Full length above the water, inches from the crew’s faces.

Shark took the whole marlin, plus a big bite out of the boat. All caught on camera. Everyone was pretty shaken for a while after.

From Redditor u/HAL-42b:

When diving, a huge seiner net drifting towards you. It wasn’t anchored or attached to anything. Just a huge whirling cloud of death, full of barnacles and dolphin skeletons and decomposing fish.

From Redditor u/YaBoyZoidberg:

Not me, but my father back in his commercial fishing days noticed that there was a T-shirt in the middle of his net after one tow. After a little investigation he found that it was not a shirt, but a human torso wearing a shirt.

He said he was terrified that he would open the net and a head would roll out onto his feet, but it didn’t happen. His captain radioed ahead and they brought the torso back to the docks, where they were met by the police and a coroner.

They were eventually able to identify the body (based on the clothing) as a victim of a plane crash that had occurred fairly recently.

My dad said he offered a free lobster to the coroner, who graciously accepted it until he found out that it had been found in the net with the body. After that he got angry and told him to throw it back.

From Redditor u/Trev0matic:

The sea is a vast and seemingly empty place. Many fail to grasp this when asking questions like, “How can you just lose an AIRPLANE in the ocean?”

I found myself on my ship somewhere in the vast expanses of the South Pacific. We had been cautiously avoiding big storms, which I knew to be ALL around us (out farther than the eye can see), although our local ocean area was calm and peaceful. I was on watch when I noticed something out there, in the distance, bobbing along – that I had never seen before, especially this far from land.

As I got closer, I identified what was clearly a makeshift raft, made from lashed together bamboo, with a snapped mast, and an empty cooler moored to the deck. Upon this raft was not a soul. The chances of coming across a raft to begin with are small enough in that part of the ocean.

Thinking about the person(s) who once sailed that raft, why they sailed, and how they met their fate – that was what creeped me out.

From Redditor u/netdude60:

I had just reported aboard my first ship. We were in port (Brooklyn, NY), and I was over the side, on a camel (a long wooden raft that kept the ship away from the pier.), scrubbing the side of the bow with a push broom.

This was in December on the East River.

The river was moving swiftly and was rough. It was a cold, dreary, crappy day! Anyway, I’m scrubbing away and looking around when I see an arm raise up from the river! Just as I start to call out about this and point, it sinks out of sight.

Everyone thinks I’m nuts now and starts to rag on me. I can still see this in my mind, though it’s been almost 40 years.

From Redditor u/Aus_:

Fishing out near the Great Barrier Reef and my brother, who gets seasick, decides to go for a swim to settle his stomach.

Less than a minute after getting back, a 17-foot great white shark went under the boat.

From Redditor u/Shashi2005:

During WWII, my dad was a wireless operator on a minesweeper. He passed by a German pilot waving frantically from his still floating aircraft in the North Atlantic. They were under strict orders not to stop because of the danger of subs. So they left the poor guy to certain death.

My dad died a couple of years ago, but this incident haunted him throughout his life. He wept about it even in his last few hours.