The creepiest for me was seeing a 12 ft. tiger shark swimming in the distance when I was diving in Hawaii. The water was clear but there was a little haze. It was just far enough away that I kept losing track of where it was. Then I would turn my head around and see it behind me again

a large Octopus came and hugged me from behind while I was free diving. I tried to take it away from me but it keeps making more pressure till its gone. it docent sound that creepy but i was really freaked out when it did, because I didn't even see it coming.

Scuba dive at night. Started feeling a tapping on the back of my head. What exactly could be doing that 30ft under water? Turned around and was face to face with a Hawksbill turtle. Guess my hair looked like an anemone or jellyfish tendrils, one of its favored foods.

Shine a torch over the side of the boat at night, 5km from the land, and 100s of tiny sea snakes. Everywhere I point the torch was a writhing mass of snakes.

I've posted this before but it's been a year, so f**k it haha So this is proper babby's first free dive material and I've since learned I'm terrified of the ocean, so this probably isn't that scary to most people. However... I was on a boat tour that stopped off in a small bay with f*****g beautiful, crystal clear, light turquoise water and nearly white sands. We'd just finished swimming with some sting rays when the tour guide offered to take some of us out for a swim in deeper water. I was hesitant as he said the current can get quite strong and I'm not the best swimmer, but he said I could join them for as long as I felt comfortable, so I came along. There was a small group going at a leisurely pace that I could clearly see, so I decided to do some free diving. As I said, the water was gorgeously clear. I was diving down to these little reef outcrops and checking out the fish and had barely looked ahead of me other than to check on the group. I finished inspecting another little coral group and turned around to see where the group were and suddenly saw the sandy sea floor disappear over a knife sharp drop off. The water was so deep and inky blue with no sea floor in sight and my stomach somehow dropped into my a*s and jumped into my throat at the same time. I surfaced ASAP and got as far away from the drop off as possible and tried to pretend I never saw it.

Not a professional "water person" and not horrifying but when I was kayaking on a lake somewhere in south Dakota there was a gigantic floating tree trunk with massive roots I thought it was a kraken and nearly fell into the water

Pretty much anything that moves under the water is creepy if my head is above water. Under the water it's the opposite. Nothing bugs me. I've gone diving with sharks many times. They don't make me nervous at all. Jellyfish do though, especially in southeast Asia. The one time I was really spoked was skin diving in the Galapagos. I went down quite deep (for me), maybe 6-7 meters. I see an absolutely massive manta ray lying on the sea floor. Bigger than me by maybe 40 kilos, maybe more. Continued on my way, looking at the colourful fish. When it came time to ascend, I turned towards the manta again. It had been tracking my movement and moving towards me. When I looked at it, it stopped. I felt like it was up to no good. It felt very threatening. It didn't like me being there or something. Maybe it thought I was lunch. Dunno. I got the f**k out of the water and went to have a beer to calm my nerves.

I’ve dove a number of wrecks that were graves (many lives lost / remains still in the wreck). Spookiest though would be diving through a large ship that was lying on its side (so easy to get disoriented). Inexperienced diver in front kicked up a bunch of silt so even with a torch it was black-out conditions and no chance to see where the guide was or know the way out.

I went surfing at Malibu pier one night. As I was suiting up, a bunch of guys hanging around a uhaul truck kept eyeing us. A little creepy, but f**k it, I paddled out. Not ten minutes later I heard a motorboat out of nowhere going fast as f**k with no nav lights. Crashed right onto the beach, only to be met with a bunch of dudes with flashlights. I was worried but seemed like it was being taken care of. Got out of the water a little later and the boat was abandoned and the uhaul disappeared. Turned out it was a cartel drug run from Mexico. Just happy they let me be.

I was Scuba diving at a shipwreck, awesome experience. Very dark though which had me on edge. Not a very well preserved wreck but it was awesome to see everything down there. There was a huge expanse of open water to the side of the wreck that kind of began to slope off, and as we left the wreck we saw a huge tiger shark floating in that open water. My friends and I just swam back to our ship slowly and it didn’t really follow, but if you know anything about tiger sharks, you know how aggressive they can be, and how menacing one would look in dark water. Seeing something like that, in that environment, with that level of darkness (it was the evening) is terrifying. The fact that it could hurt you if it wanted and you can’t do anything about it makes it 10x worse. All you can really do is keep calm and keep your distance. Remembering this around large dangerous aquatic creatures has always worked for me and I’ve never been harmed. In hindsight, it was a very beautiful moment but I def didn’t think that at the time.

I encountered a moray eel chomped in half on a night dive. Eel was still swimming.

I do a fair bit of cave diving in North Florida and help out with exploration projects. I've got a couple. One is mine, one is a friend's. So my friend was checking a lead in an offset sink to see if there was any going cave one afternoon. Offset sinks are physically distant from the main cave conduit, so while a primary trunk passage may have lots of clear ground water, an offset sink won't get much water circulation, so rainwater and runoff will tend to stay there for a long time. They're typically very murky and brown, clearing as you approach main cave passage. He's about 100ft in at a depth of 40 or 50ft. Nothing insane, but it's braille diving. Trying to feel his way around while running a line to see if anything goes. He comes across a wall about a foot in front of him that looks a bit unique. Often times you'll see cool patterns of mineral buildup in cave walls/floors/ceilings. So he's appreciating this cool pattern when that pattern opens its mouth and shows off its teeth and tongue. Turns out a not insignificantly sized gator lived in that sink and wasn't happy about the home invasion. He set a new speed record getting back to the surface of that particular sink. Gators aren't uncommon down there and they usually leave you alone, but not when you get that close to them in their own territory. My story was a bit less exciting but pretty somber. I was doing a dive in the back of a fairly regularly traveled cave system, but in an area where a body had been recovered from about a mile back the week prior. That area isn't as regularly dived due to the logistics and cave passage geometry. It's not a small dive to get back there. The recovery was really challenging and there were signs of damage to the cave as we swam along where the body had been forced through restrictions, through mud, etc. But the real reality check came when we found his mask in the mud several thousand feet back. It had been dislodged (along with his nose) while the recovery divers tried to force him through a small area. It really drove home the reality of where I was and what I was doing and the respect necessary for the environment.

There were days/nights out on the Persian gulf when the sea was perfectly calm and looked like glass. The stillness always gave me the creeps for some reason.

Scuba Diving in Vanuatu on the President Coolidge, very famous wreck dive that you can walk from the shore and dive the bow from 15 meters all the way down to 70 meters. I was 14 at the time and my parents were life long divers, we dived the Coolidge twice that day already and our guide offered a night dive to us. We were supposed to only dive down to a depth of 25 meters and check out these flashlight fish that would school together in a cargo hold, they had these really bright green eyes that looked amazing and lit up underwater. I still don’t really know what happened that night but it felt like we were staring at these fish for forever. Suddenly I didn’t feel right, my breathing felt funny, I tried to grab my gauge to check how much air I had left, it took every bit of muscle I had to reach for my gauge connected to my waist, I slowly grabbed it and read that I had about half a tank left, relived for a split second but still concerned something was wrong I reached for my mum to signal her something wasn’t right, I grabbed her arm but couldn’t hold on, I just started sinking to the bottom. My mum quickly grabbed my arm as I fell but I had no leg movement, so I started dragging her to the bottom with me, my dad now realises somethings wrong and grabs my mum trying to pull us all up. The dive guide now is freaking out and trying to make sure everyone is alright, they all start swimming me back up and in to shore. Once we got up closer, I started to feel normal again but abit dazed and confused. Turns out I had nitrogen narcosis, and had dropped to 40 meters when I couldn’t swim anymore. For those of you who don’t know what nitrogen narcosis is, it’s when you have to much nitrogen in your body and it gives you a intoxicated effect. Nothing to hectic but still a vivid memory of thinking I was gonna sink to the bottom of the ocean not being able to do anything about it.

Was doing a deep dive certification with an instructor in Dahab, Egypt. We went down to 40 meters and i did a math test to check if i was thinking straight or narced on nitrogen. I aced that test! Performed it faster and better then on the surface in the comfort of an air-conditioned classroom. My instructor was happy and we carried on with the slow ascend. Little did i know that i was completely narced and confused the button that blows the BCD up with the one that dumps the air. Basically i was sinking vertically without even understanding my mistake. That’s when the instructor came to my resque and everything ended up well. Best part of the whole experience - it was all on film and the people in the dive center saw it and kind of congratulated me on being alive. When i saw the video i was amazed at how happily stupid i looked. Smiling and kicking my fins thinking i am going up while actually descending deeper. That was a good lesson for me not to underestimate the nitrogen narcosis and the effects it has on the mind.

Super tame compared to the rest of these but I was night snorkeling in the maldives with a torch on the reef, far enough from the island that it would have been pitch black without the torch. Really fascinating wildlife down there at night. Decided to enjoy some sensory deprivation so I turned off the torch and just floated for a bit. When I turned it back on the first thing I saw was a huge reef shark headed straight for my face. They're pretty harmless but that took a sec to register

Had a pod of dolphins swim under me and my friend, grazed our legs. The waves sucked, we were just hanging out on the boards. Immediately thought bull shark or nurse, checking if we were food. Then we saw dolphins popping up. They were just passing through I guess.

I was surfing scripps pier in San Diego about 6 years ago. It was flat, onshore wind, really messy conditions but I spent 40 min driving there and said “ I’ll just get in the water and paddle around a bit”. There was nobody in the water. I decided to paddle around the pier, going from the north side to the south side. When I reached the last pylon, a HUGE fin popped up about 5 feet in front of me. I knew instantly it was a massive white shark (12-15ft based on the size of the fin)- I’ve been surfing my whole life, I’ve been in the water with dolphins many times. This was 100% not a dolphin. This fin was more triangular with a serrated back side (almost like a steak knife) with a sandpaper looking texture. Dolphins have more scoop in their fin and very smooth texture on their skin. The way it swam gave me instant chills- fishy, more side to side and straight than the classic up and down, coming up for breath dolphin. I froze. Trying to control my panic, waited for it to disappear and as smoothly as possible, turned my board around, paddled through the pier back to land. It was absolutely checking me out but didn’t show any interest towards me. Since then, I’m not that afraid of sharks but I still get the chills thinking about that day.

Asked my scuba instructor this question years ago. He liked night diving. Found a cave that he measured using his divelight, moving it 3 times around to get the entire view. Seemed to look like a prehistoric turtle chilling inside.Then we went river diving.

I dive every once in a while, and I once saw a bobbit worm Do not look it up if you want to sleep

I remember a couple years ago, a buddy of mine had rented a boat out for my birthday to go out in the sea with. It was going perfectly fine, the boat was super nice, good for fishing, had a great deck. When he told me he was going to rent one, i thought to order a new fin to scuba with. It was a mono fin since i had never gotten a chance to use one. I’ve been practicing with it, so it was perfect to use it out in the sea. We started to go out off the coast of the cape and the water was a bit chilly, but not ice cold. we were maybe 22 miles out from the coast while still having an eye sight of the shore. My friend brought fishing baits and rods for us to use later on, but after i was finished scuba diving. I was ready to get off the deck of the boat with my wetsuit and mono fin, my tank resting on my arm before i was going to dunk in. After a couple minutes, i had this really weird chill down my spine. Not paranoia, but superstition. I brushed it off and put my tank on my back, followed by my goggles. I felt that weird superstition feeling again but it quickly switched to paranoia when i saw a pair of glistening eyes in the ocean. At first what i thought was a shark, it had not been a shark. I’ve had my fair share of training for 6 years with sharks and other deep ocean water creatures, so i thought i’d be able to handle this. It slowly started making it way towards me when i got a better glimpse at it, it was HUGE and i mean massive, it’s teeth were poking on the side of its jaw and even had razor sharp fins. And how i know this wasn’t a shark because they have a more smooth rubbery type of flesh, this one had scales like a snake. Blood was pouring out of its mouth, it looked like it was ready for its next meal. I attempted to hurry, but i was in shock and i thought i was to die from shock or from this thing eating me. I finally cut out of shock the moment it started to swim more swiftly, but the mono fin could only go so fast in the water. My buddy was getting a little suspicious that i hadn’t come up with anything from the depths of the ocean. He looked over the boat deck and i guess could see me attempting to swim for my life as a dark shadow was inching closer. I eventually reached the boat and out of breath i told him to book it. we ended up not using the boat for the rest of the day and went home. To this day, i have no idea what it was, but in all my years of experience, i dont want to find out.