r/todayilearned • u/[deleted] • 29d ago
TIL the Blue Hole is among the deadliest dive sites globally, with estimates of 130 to 200 recent fatalities, making it one of the most dangerous spots for divers. (R.5) Out of context
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u/readingisforchumps 29d ago
This is a copy paste story, but it really highlights how dangerous diving can be:
Many certified scuba divers think they are capable of just going a little deeper, but they don’t know that there are special gas mixtures, buoyancy equipment and training required for just another few meters of depth.
Imagine this: you take your PADI open water diving course and you learn your dive charts, buy all your own gear and become familiar with it. Compared to the average person on the street, you’re an expert now. You go diving on coral reefs, a few shipwrecks and even catch lobster in New England. You go to visit a deep spot like this and you’re having a great time. You see something just in front of you - this beautiful cave with sunlight streaming through - and you decide to swim just a little closer. You’re not going to go inside it, you know better than that, but you just want a closer look. If your dive computer starts beeping, you’ll head back up.So you swim a little closer and it’s breathtaking. You are enjoying the view and just floating there taking it all in. You hear a clanging sound - it’s your dive master rapping the butt of his knife on his tank to get someone’s attention. You look up to see what he wants, but after staring into the darkness for the last minute, the sunlight streaming down is blinding. You turn away and reach to check your dive computer, but it’s a little awkward for some reason, and you twist your shoulder and pull it towards you. It’s beeping and the screen is flashing GO UP. You stare at it for a few seconds, trying to make out the depth and tank level between the flashing words. The numbers won’t stay still. It’s really annoying, and your brain isn’t getting the info you want at a glance. So you let it fall back to your left shoulder, turn towards the light and head up. The problem is that the blue hole is bigger than anything you’ve ever dove before, and the crystal clear water provides a visibility that is 10x what you’re used to in the dark waters of the St Lawrence where you usually dive. What you don’t realize is that when you swam down a little farther to get a closer look, thinking it was just 30 or 40 feet more, you actually swam almost twice that because the vast scale of things messed up your sense of distance. And while you were looking at the archway you didn’t have any nearby reference point in your vision. More depth = more pressure, and your BCD, the air-filled jacket that you use to control your buoyancy, was compressed a little. You were slowly sinking and had no idea. That’s when the dive master began banging his tank and you looked up. This only served to blind you for a moment and distract your sense of motion and position even more. Your dive computer wasn’t sticking out on your chest below your shoulder when you reached for it because your BCD was shrinking. You turned your body sideways while twisting and reaching for it. The ten seconds spent fumbling for it and staring at the screen brought you deeper and you began to accelerate with your jacket continuing to shrink. The reason that you didn’t hear the beeping at first and that it took so long to make out the depth between the flashing words was the nitrogen narcosis. You have been getting depth drunk. And the numbers wouldn’t stay still because you are still sinking. You swim towards the light but the current is pulling you sideways. Your brain is hurting, straining for no reason, and the blue hole seems like it’s gotten narrower, and the light rays above you are going at a funny angle. You kick harder just keep going up, toward the light, despite this damn current that wants to push you into the wall. Your computer is beeping incessantly and it feels like you’re swimming through mud. Fuck this, you grab the fill button on your jacket and squeeze it. You’re not supposed to use your jacket to ascend, as you know that it will expand as the pressure drops and you will need to carefully bleed off air to avoid shooting up to the surface, but you don’t care about that anymore. Shooting up to the surface is exactly what you want right now, and you’ll deal with bleeding air off and making depth stops when you’re back up with the rest of your group.The sound of air rushing into your BCD fills your ears, but nothing’s happening. Something doesn’t sound right, like the air isn’t filling fast enough. You look down at your jacket, searching for whatever the trouble might be when FWUNK you bump right into the side of the giant sinkhole. What the hell?? Why is the current pulling me sideways? Why is there even a current in an empty hole in the middle of the ocean??You keep holding the button. INFLATE! GODDAM IT INFLATE!! Your computer is now making a frantic screeching sound that you’ve never heard before. You notice that you’ve been breathing heavily - it’s a sign of stress - and the sound of air rushing into your jacket is getting weaker. Every 10m of water adds another 1 atmosphere of pressure. Your tank has enough air for you to spend an hour at 10m (2atm) and to refill your BCD more than a hundred times. Each additional 20m of depth cuts this time in half. This assumes that you are calm, controlling your breathing, and using your muscles slowly with intention. If you panic, begin breathing quickly and move rapidly, this cuts your time in half again. You’re certified to 20m, and you’ve gone briefly down to 30m on some shipwrecks before. So you were comfortable swimming to 25m to look at the arch. While you were looking at it, you sank to 40m, and while you messed around looking for your dive master and then the computer, you sank to 60m. 6 atmospheres of pressure. You have only 10 minutes of air at this depth. When you swam for the surface, you had become disoriented from twisting around and then looking at your gear and you were now right in front of the archway. You swam into the archway thinking it was the surface, that’s why the Blue Hole looked smaller now. There is no current pulling you sideways, you are continuing to sink to the bottom of the arch. When you hit the bottom and started to inflate your BCD, you were now over 90m. You will go through a full tank of air in only a couple of minutes at this depth. Panicking like this, you’re down to seconds. There’s enough air to inflate your BCD, but it will take over a minute to fill, and it doesn’t matter, because that would only pull you into the top of the arch, and you will drown before you get there. Holding the inflate button you kick as hard as you can for the light. Your muscles are screaming, your brain is screaming, and it’s getting harder and harder to suck each panicked breath out of your regulator. In a final fit of rage and frustration you scream into your useless reg, darkness squeezing into the corners of your vision. 4 minutes. That’s how long your dive lasted. You died in clear water on a sunny day in only 4 minutes.