Former saturation diver here, got some stories.

Used to do saturation diving. I did work on oil rigs. It's pretty spooky down there. No particularly "spooky scary seamonster" stories, but it's not a nice place.For one, it's dark as a MOTHERFUCKER. Pitch black and your lamp barely goes more than a few yards effectively. The water is filled with particles so it's kind of like shining a light into smoke. It's seriously like being in a void and the only things in this void are you and the rig. I never disconnected from it longer than I had to. It just feels like you can fall forever.As for spooky scary seamonsters, I never really saw any. Don't get me wrong, you see shit a lot. The mixture you're breathing combined with the pressure can and will fuck with your senses. More than a few times I saw something big and fast moving just beyond my light. Sound doesn't travel well in water but you can hear the rig popping and other shit, always really deep tones.You see a bunch of really weird fucking fish though. No joke, divers usually see a lot of fish that aren't identified. The aquanauts have to do that but they can never get the funding to come down and see what we see, so we just live with the aliens. We named a few but you don't really see them often and rarely more than two or three times. Some fish are drawn to the lamp, but others stay the fuck away from it.I think the most interesting is what the mixture and depth does to your brain. When you've been out in the water for a while and literally only you and the piece of metal you're clinging to are the only things that seem to exist, your brain tries to fill the void. At least, I hope it was my brain doing that.The rig popping is really ominous because it's like a bass drum that's all around you and the only sound in almost absolute silence. You can see things moving in the dark and when you look at them, your lamp only goes ten yards or so and all it's hitting are the particles in the water. This happens a few times and you're certain you're not alone down there. You feel like you're being hunted. A lot of guys die because they try and rush and that's something you can't do underwater, no matter how much you want to. You kind of got to get it in your head that "well shit I hope it doesn't eat me" and keep working. It can be hard not to panic. They teach you tactical breathing both to conserve and to keep you from losing it.You start focusing really god damn hard on that tactical breathing when you swear you saw something on the edge of your vision, felt the water move against your back, and heard the shift.Another story came to mind: I was out doing my job one time in the absolute darkness of the void. I had been out a good thirty or forty-five minutes when I saw something swish over the top of my vision really fast. I looked around, couldn't see anything. Spooked me good and so I just focused on my tactical breathing and not losing my fingers. A minute passed and I saw something go a little behind the pylon and down. I was 100% sure it was a kraken or some shit. Another minute passes and then this two or so foot fish comes swimming up to me. Weird looking motherfucker. Pale and long and skinny with BIG eyes and a bigger mouth. It just kind of darted around me for a bit, just hanging out with me while I worked. When I was done, he took off. Cool fish bro.I told the story to a buddy of mine and he suggested that the fish hung around me because of my light. A lot of things don't approach the light down there. He was probably using me for shelter from something bigger and meaner. How terrifying.On the topic of death: The pay was good but the only place it could really get you was dead eventually. I know of many people who died and I personally knew two. One panicked while he was working, as I understand, and fucked himself up. Getting hurt down there is a death sentence. You can't get back up in time to get patched up. My other buddy died because they fucked up his mixture. You can't put too much oxygen in the tank because it doesn't react well at depth. He went down and had a seizure due to it. Big investigation after that one.I think the closest I ever came to dying was when I went on an excursion, which is where you go to a different depth than the bell is at, and was about to come back up when I got tangled in my gear really bad. I lost track of it as I went back and forth around the pylons. Normally it's pretty easy to get out of, but it got caught under my helmet which is bad for a variety of reasons. Also, when you're tangled and it's not taut, you can fall or rise without noticing. So basically I had to carefully unweave myself without snapping any harness or locks while I fell into this bottomless abyss. It was actually pretty terrifying. Tactical breathing at its finest. I obviously made it out okay.