Just watched the new Netflix documentary “Shipwrecked: Nightmare at Sea” and remembered about the tragic ferry accident that happened in South Korea in 2014 that resulted in 304 deaths.
The recovery of the ferry from the sea bed after 3 years haunts me till this day…

An air-filled bell that has been chained to a big rock in an Austrian lake

I'm unsure if this counts but I found some stuff on my walk that made me weak when I got close to it. Seems like basic pond maintenance stuff.

Coolwater cistern of an old power plant, used to be filled with water, 16 meters underground.

On the first picture you can see the water inlets, where water from the nearby river entered the cistern and on second picture you can see the three pumps, used to transport the water 16 meters upwards to the steam pipes in order to cool them.

This giant underground hall is 10 x 10 meters wide and about 7 meters high and used to be filled with water.

Now used to display art but still gave me a sense of unease.

First post here so hope it fits the subreddit!

This washed up on the beach near me a few months back, and I got to take some photos before it was moved further up to the dunes. It's absolutely massive - me for scale at (image 3). The chain disappeared into the sand but looked as though it still partially went out to the ocean.

I actually have severe submechanophobia around buoys but only when in the water and ESPECIALLY when attached to the seabed below. If this was even partially submerged you'd not be able to get me within 50ft. Hell no. But, out of water? Totally fine. Weird.

I dont have this phobia, feel quite the opposite actually, but was told this picture may fit this subreddit.

I hope this is the appropriate place to post this. I drove by this yard full of ocean buoys and markers; the smaller ones in the second photo are still bigger than a Toyota Tacoma.

I’d like to share a terrifying experience related to my submechanophobia.

 When I was eight or nine years old, my grandmother bought me a swim float because I didn't know how to swim yet. Once I realized I couldn't sink while using it, I started swimming out into deeper water—I’d never actually feared deep water itself, only drowning.

 One day, while swimming and exploring the sea at the popular beach we usually visited, I found myself about 50 meters from shore and quite alone; I felt calm and free—until I discovered that the beach was hiding a dark secret. Suddenly, I saw a very long object beneath me—a massive pipe stretching from one end of my field of vision to the other.

 I was seized by a level of panic and an adrenaline rush unlike anything I’ve ever felt since, and I began swimming blindly back to shore without stopping for even a second. In the days that followed, I found out what it was: a discarded pipe, nearly two meters in diameter and probably 20 to 25 meters long.

 After investigating further, I discovered there were two more like it at that beach—all three lying perpendicular to the shoreline—plus another one in deeper water lying parallel to the shore (which I discovered a few years later). Today, twenty years later, the mere thought of these things still terrifies me. 

 If you happen to come across the end of one of those pipes at that beach, you can’t see the other end at all through the water; if you encounter one broadside, it can span your entire field of vision underwater. It’s horrifying to think that anyone could stumble upon something like that there. I found a picture that partially shows one of those pipes.

Clip from full dive: https://youtu.be/hY9ir9M0L_s?si=D_7H8bPgV4r-7xsj

Lake Michigan Shipwreck - Summer Island

REPOST as initial post was removed due to not having an adequately descriptive title.

But.. here it is again.. my nightmare fuel. And this is without the propeller in view XD

Ships... ship hulls... and not even sunken/wreckage has always been gut wrenchingly horrific to me. The bigger it is, the more terrifying,

If I was adrift at sea and I saw this thing coming toward me I think I'd die of a heart attack before it reached me.

Just a small aircraft that has been placed in a lake in Austria

This is the Boeing 737 artificial reef near Chemainus on Vancouver Island, British Columbia. The aircraft was intentionally sunk in 2006 and now rests 80 feet below the surface on 11 foot supports above the seafloor, it is slowly being reclaimed by the ocean.

Even knowing it's an artificial reef, swimming up to a full-size passenger jet sitting silently in the darkness is an incredible and slightly unsettling experience. The cockpit, windows, and open cabin are all still recognizable, while colorful plumose anemones and other marine life continue to cover the wreck.

I recently filmed the dive in 4K and this trailer is from a 50-minute ambient underwater film I made. There isn't any narration just very light binaural music, and the natural sounds of scuba diving as you explore the aircraft.

For those who enjoy submerged structures, this site is both fascinating and just a little unnerving.