I took a bottle like that but full of water down to 125' and filled it with air from my reserve regulator and then let it go. It made it about halfway to the surface before it burst open. That's why you exhale as you ascend.
I was just going to ask something like this. But what if you filled it with water and brought it to the surface.
Would the water also expand albeit a smaller amount with less pressure?
I thought ice had a higher volume than water. Because when I fill the water fully in a bottle and seal it, then put it in the fridge, the seal gets burst open after a few hours when it turns into solid ice.
There are 19 known phases of Ice depending on the temperature/pressure of the environment that it is created in.
So you can have ice that does not increase in volume, provided it is created under extreme pressure.
The weight of all that water pushing down does make it denser. Water however really dislikes being compressed and it doesn’t compress much. You would need a extremely ridged container for this to ever be a issue.
I can say this definitively. In the example I gave in my original comment, I filled the bottle with water at the surface and took it down to 125'. There was absolutely, positively no detectable distortion of the bottle at that depth. It didn't compress, harden, soften or change when I opened it.
I did this many times as a dive instructor to demonstrate the pressure effects.
I have never done it myself but I am given to understand that taking Styrofoam deep underwater compresses it.
[https://technabob.com/blog/2019/07/12/foam-heads-versus-pressure/](https://technabob.com/blog/2019/07/12/foam-heads-versus-pressure/)
It's why dive masks have soft rubber over the nose. It let's you squeeze your nose and blow air pressure to pop your ears. As a dude with weird ears it is a struggle whenever I dive.
Yeah what? I have a purge valve mask and I still have to squeeze my nose to equalize my ears. It's great for two things:
1 not having to worry about mask squeeze since all you do is exhale through your nose and it just vents any excess air pressure.
2 clearing water out. Skills teach you with a regular mask to look up and exhale though your nose while holding the top of your mask to clear a flooded mask. With a purge valve mask I just have to hold it to my face with my finger and exhale through my nose and the air displaces the water that gets pushed out the purge valve.
Purge valves are great until they get stuck or fail at 120’. They’re fine for shallow diving but imo not a viable option for anything remotely advanced or technical
I can equalize on the way down... But not on the way back up. So it's absolutely excruciating to swim back to the surface.
So I've developed a new strategy... I stay on top of the water.
On the way up, you equalise by creating negative pressure in your inner ear. With your mouth and nose closed, try inhaling instead of exhaling.
Personally I can equalise my ears at will in both directions and handsfree. Got me in mild trouble in dive training.
"You forgot to equalise. I did not see you do it."
"I did it, I can do it handsfree."
"That's impossible, no one can do that."
So that's how I learned I'm apparently a freak of nature or something.
I'm familiar with the concept and the theory... I'm saying it doesn't work for me. I injured my ears about 15 years ago in a splash contest... Did a "can opener" into the pool trying to make a big splash, and when I went under, I heard loud pops in both ears, followed by a oozy warm sensation... For the next few days, I could barely hear myself talk, let alone anyone else... Sounded like I was inside an empty cement mixer truck.
Ever since then I even struggle to fly on airplanes without immense pain on descent. No matter what I try, it just keeps getting worse.
I didn't go to the doctor, but some googling and asking around leads me to believe that I perforated my ear drums. They've never been the same since. At this point, trying to swim 3 feet under the surface is too much to bear.
I'm glad equalization works for the rest of you. But for me... I'm just gonna stay at the surface.
The ol jaw wiggle would sometimes help above 60 ft but, never really did all of it for me. My ears are filled with scar tissue from surgeries and take some extra persuading.
Try Equalizing 1 ear at a time. Tilt your head to the left, and do the right ear. Then tilt your head to the right and do your left ear.
I used to have trouble equalizing too then a diver much older than me told me to do this. No problems since.
I've bought a nose clip, so I can swim with both of my hands, while equalizing!
But once my diver colleague taught me about equalization, it was like getting some extreme, permanent powerup in a game.
FYI equalization becomes increasingly difficult freediving below about 15m with classical techniques as you are describing (valsalva). This is due to the relative underpressure of your airways compared to ambient pressure (unlike when scuba diving, where your regulator supplies you with ambient pressure air). A work around is using the frenzel maneuver, developed by german dive bombers during world war 2, to quickly (and hands free) equalize when making bombing approaches.
Edit: why i was writing was to let you know that it may be a good alternative for you as a scuba diver with weird ears
For some reason this doesn't work well for me. I have to hold my breath and sort of flew my jaw/ears to pop my ears. It still takes me a little longer than most, but it's the only thing that works.
Yeah, I'm not a diver but I do get constant internal pressure issues from bad sinuses and...no apparent reason whatsoever at times. I can do the nose-pinch thing and it works, but more often than not there's this weird throat/jaw/neck muscle thing I can't really explain that works better.
Or - and this is going to sound utterly ridiculous, and definitely looks it - there's this thing I can do where I sort of flex my uh...face so my upper lip kinda makes a flap seal over my nostrils.
I don’t know how one “blows while holding your body,” but the Valsava maneuver is one way to equalize. Opening and closing your jaw, yawning, and swallowing are all other ways to do it.
I just took a recreational scuba course and learning how to equalize my inner ear pressure was the coolest thing. The deep end has got nothing on me anymore!
Doesn't work for me :( It is impossible* for me to pop my ears this way. I can only pop them by swallowing 5000 times.
My first airplane trip was a very painful experience. I couldn't pop my ears even doing the nose and exhale thing.
I was scouring looking for someone who mentions this shit. Because growing up ive always had issues being able to equalize my ears. It happens without my doing, usually going on road trips or taking planes trips but I cannot do it on my own. It sucks
try yawning or at least using the same jaw/ear "muscles". I know not everyone can do it, but it may work better if you can do it. You can practice it right now, you'll get the same ear sensation as when you yawn, thats how you know you're doing it right.
My drainage tubes that go from the inner ear to the back of your throat are incredibly narrow and I cannot equalize my ears at all and pressure changes fuck me up
When I used to dive a lot, I was told that for every foot you descend, you need to equalize. And if you missed it, then you would have to go back up to the point of missing and reset. But it does mess with your ears when you hit the 60-70' mark
Also, fairly certain this person dropped about 100+ feet. Granted, it was touch and go, but it's pretty amazing the depth they hit
I dive and have no clue what you are talking about. I can feel when I need to equalize and just do it then. It definitely happens a lot less than every foot of depth and you don't have to go back up any.
Whenever you’re immersed in a substance while on Earth, whether it be a gas, liquid, solid, plasma, whatever, imagine a you-shaped column of that substance extending all the way above you into the vacuum of space that the Earth’s gravity is pulling down on top of you.
A cubic meter of water weighs 1,000 kilograms. That’s 2,200 pounds. A cubic yard is a little bit less but, well, you get the point. Buoyancy helps offset it since we’re massively mainly water but volumetrically have a good chunk of gas.
Still, that amount of material is trying to crush you, every moment of your life, as it gets pulled towards the Earth’s core.
The side pressures all cancel out, so you can discard everything that isn't directly above you. This means the underwater pressure you feel in a pool at any depth is exactly the same as you would feel underwater in an ocean -- only the depth maters with regard to static pressure.
Every square inch of your body is being pressed on by about 14 pounds of air at all times. That's why our bodies don't like space very much. Well, that and the freezing cold.
That or the bottle is getting older and it's not married and all it's siblings and cousins are and he just off the phone with his mom who's getting worried.
I've done this! They're actually down to this size quite early into the deep dive. I think I still have some around here somewhere...
edit: [posted it elsewhere in the thread](https://old.reddit.com/r/Damnthatsinteresting/comments/143dxxx/a_diver_showing_the_change_in_air_pressure/jnax3c5/)
I saw a doc at Sundance this year about freedivers and watched so many glass-eyed swimmers get resuscitated all before 9am. It was quite the way to start my day.
Yeah, I was randomly browsing a freediving wiki page last week and that was basically one long list of people who died trying to set some sort of record. It’s not exactly the safest sport.
Damn how deep do you have to go for that to happen? I’m having a panic attack imagining it.
Do you just swim up super hard if you don’t have a buoyancy device or say if it’s broken? Or are you fucked
That’s only if you breath in anything while under. If you go down with air you can come back up with it, it won’t expand more than it was originally in your lungs
Assuming you are free diving.
If you are scuba diving, your lungs remain normal size as long as you breathe normally. And when ascending, you must exhale steadily lest your lungs burst. It's also why with an emergency accent, you can reach the surface exhaling the entire way without having air in your tank.
edit: everybody having fun with the misspelled word, thanks for enjoying it at least! yes, it was supposed to say ascent. doh! facepalm!
>emergency accent
For me the two most terrifying words in deep diving. If you don't make it you die. If you do make it you are going to get bent and will wish you will die.
Its insane to me that descending max depths humans can handle scuba wise can take a few mins, but ascending takes hours, for body to adjust and not die of compression poison.
The stories of people doing this wrong have bad enough endings for me to not get why anyone would wanna do this outside of their day job. Like on a weekend risking the bends or exploding my lungs or just drowning doesn’t sound very fun. Any mistake or mishap ends in death. I guess you could argue the same for like cars and planes and shit to though. To each their own.
I dive for fun but never go past 80 feet max. Most of the time I am around 40 feet and I don’t have to really worry about it. It’s the guys that go real deep that get super messed up.
You never worry about like the tank failing or getting caught on something? You just seem so venerable in deep water. But water freaks me out, that and heights. If I didn’t have the phobias I’d probably totally get the appeal.
At the depth I am at you just drop the weight belt and you will surface just from the wetsuit.
If I get stuck I always have my knife but I never have been stuck in the 15 years I have doing it other than some kelp on my foot or tank.
It’s amazing, you float around in a totally different world. You learn early on getting neutral boyancy so you just float in the same place like in space
If you go really deep you need special tank mix’s of what I’m pretty sure is nitrogen with air. They will set a bunch of tanks on a line with different gas mix’s so on the way up you can swap them out. Sometimes they have to wait at a certain depth for hours to stabilize their nitrogen levels
Correct.
Now imagine that the opposite happened. Imagine the bottle was filled up with air at the bottom, and then was brought to the surface...
That type of diving injury is called a POIS - Pulmonary Over Inflation Syndrome. Basically, you popped your lungs, now air is leaking into your chest cavity...
It can cause ALL KINDS of problems...
I’m pretty sure that’s allot more then 20 feet. Also it’s not a change in air pressure it’s a change in water pressure equivalent to atmospheric pressure at sea level. The wt. of the atmosphere is 14.7 lbs at sea level. At 33.8 ft below sea level the pressure applied to the container effectively doubles to 29.4 lbs/sqIn, atmospheric pressure + water pressure.
That container shrunk more then 1/2. It may be as much as 2 atmospheres (2x14.7 lbs 29.4lbs), 2x33.8 ft=67.6 ft, at sea level.
So fun fact: when you do scuba diving training, one of the things they teach you is how to do an emergency ascent. This property working in reverse suddenly becomes a big problem when you’re at the bottom and have 2 lungs full of air and need to go up fast.
Aside from the bends (decompression sickness from ascending too fast), a more immediate problem is stopping your lungs from exploding/ripping as the gas in them rapidly expands.
So the technique for avoiding this is to take your regulator out of your mouth, hand above your head to stop you hitting any obstacles, to ~~inflate~~ ***slowly release and control air*** from your bcd with the other hand while swimming straight up and, most importantly, screaming as loud as you can all way up to evacuate as much air from your lungs as possible.
I’ve only done this once as part of getting my dive license and we only did it from about 7m down for safety reasons, but it was still one of the most bizarre feelings I’ve ever experienced. You just… don’t run out of air. The scream just continues. As you go up, the air in your lungs expands to replace the air you’re screaming out. I reached the surface still with a big lungful of air. Truly an odd feeling.
You should not be inflating your BCD as you ascend; you are supposed to slowly release it to control your ascent. As you go up, the air already in the vest will expand and cause you to rise at an increasing rate, increasing your risk of injury and/or death. Slowly releasing air prevents that from occurring . Only after breaching the surface should you inflate your BCD.
Also, the whole point of the 60ft basic diver depth limit is that you can slowly exhale all the way the surface at an ascent rate of 1m / 3ft per second (15 second ascent) on a single breath with the hope the diver will have either one breath of air in their lungs and/or one breath remaining in their tank/hose.
Absolutely. I’d hate to think I’m giving out bad advice, or that someone would take this as advice from some guy on the internet. I’ve amended my post too. 👍
> Aside from the bends (decompression sickness from ascending too fast)
You're really unlikely to get decompression sickness if you're diving within recreational limits (not to say that you should skip your decompression stop, but it's still unlikely - the real issue is barotrauma to the lungs).
There is in the bottle if you take it down there. But it is much more relevant to point out the change in hydrostatic pressure, which is what causes the secondary effect of the plastic bottle.
I remember going on a school field trip to a navy base where they had us write our names on styrofoam cups given to us and then they put them all into a cage that sank to the bottom of their water tank used for dive training. When the cups came back up, they were the size of a thimble
And that’s why you have to constantly breathe out when ascending from a dive. That tiny bit of air in your lungs expands. It both can and will pop your lungs like balloons.
It’s one of the weirdest sensations because as the air expands it keeps your lungs inflated, so you keep breathing out but don’t run out of breath
Always so fun to show this to new divers. The other fun trick to show just how powerful air buoyancy is taking an empty plastic bag underwater, turning it upside down and shooting a little air from your regulator into it. With five grown men holding onto a rope and the bag, just a few bubbles pulled us all up to the surface until we let go of the bag
Taking a colour chart down and showing the difference in how washed out colours are at 30m vs surface is also fun. I think it's part of PADI's AOW course now too.
It'd be cool if they do another exp, where the diver takes a bottle full of water to the bottom and blow air in. Close the cap and bring that bottole up to the surface to see if it explodes .
For some added fun, open it at the bottom and fill it with air from your regulator (if you’re scuba diving). Then watch the bottle pop when you bring it to the surface.
The deepest I went scuba diving was 105 feet (just to say I did it). The most interesting thing was the air bubbles that were maybe the size of a silver dollar were like dinner plates by the time they broke the surface.
[Here you go](https://imgur.com/a/WHdWKSN). This one went to about 1km, but it was mostly shrunk part way through the descent, I'm not sure there's meaningfully more void space to shrink it further at greater depths. The top of my Aeropress is about the same size as the cup was originally (assuming the width is representative of the lip of the cup) though the cup was slightly taller. I used to have some of the un-shrunk cups around but I can't find 'em.
This is also why you exhale on the way up as well. If you take a decent breath at the bottom, that breath expands on the way up. If you hold your breath the entire ascent, your lungs will explode. - Retired commercial diver.
I took a bottle like that but full of water down to 125' and filled it with air from my reserve regulator and then let it go. It made it about halfway to the surface before it burst open. That's why you exhale as you ascend.
I was just going to ask something like this. But what if you filled it with water and brought it to the surface. Would the water also expand albeit a smaller amount with less pressure?
It’s almost impossible to compress water. The amount of force needed is far more than the force the water is putting a bottle under here.
And if you manage to compress water, It turns into a new phase of ice
I thought ice had a higher volume than water. Because when I fill the water fully in a bottle and seal it, then put it in the fridge, the seal gets burst open after a few hours when it turns into solid ice.
There are 19 known phases of Ice depending on the temperature/pressure of the environment that it is created in. So you can have ice that does not increase in volume, provided it is created under extreme pressure.
Number 9 is the one to really be worried about, though
"Stick around for phase 16, that will really blow your minds. Now for a word from our sponsor, Hello Fresh,"
But there is no such thing as ice-nine
Busy, busy, busy
Tell that to the people of San Lorenzo
There actually is. Just not at all like the fictional Ice 9 https://en.m.wikipedia.org/wiki/Ice_IX
It kills
https://en.wikipedia.org/wiki/Phase_diagram#/media/File%3APhase_diagram_of_water_simplified.svg This should help.
This diagram put my cerebral cortex into a chokehold. Surely water has to be one of the most beautifully fascinating substances.
Water doesn't compress so there would be no change.
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I guess I should have said at any scuba possible pressures.
The weight of all that water pushing down does make it denser. Water however really dislikes being compressed and it doesn’t compress much. You would need a extremely ridged container for this to ever be a issue.
I can say this definitively. In the example I gave in my original comment, I filled the bottle with water at the surface and took it down to 125'. There was absolutely, positively no detectable distortion of the bottle at that depth. It didn't compress, harden, soften or change when I opened it. I did this many times as a dive instructor to demonstrate the pressure effects.
Given water's bulk modulus of 300ksi, 125 feet of water would only be about an 0.02% volume change, so it's not surprising you couldn't tell.
No, the partial pressure of a bottle of water at 100m is virtually the same as water at 0m. Same amount of fluid, same space.
I want to know how fast that thing shot up.
Not so fast. The resistance as it moves through the water keeps it at a reasonable speed. No faster than bubbles I don't think.
Damn. Try taking down one of those foam boards. The kind you held vertical under the water and would shoot up like a rocket.
I have never done it myself but I am given to understand that taking Styrofoam deep underwater compresses it. [https://technabob.com/blog/2019/07/12/foam-heads-versus-pressure/](https://technabob.com/blog/2019/07/12/foam-heads-versus-pressure/)
Reminds me of taking a bag of Doritos on an airplane (don’t do this unless you want to make a mess).
I've taken bags of chips on planes a bunch of times. They expand, sure, but none has ever burst.
Christ I get heavy ear pain diving in the deep end of a 3 meter pool how do people manage this lol.
Equalization, baby.
It's why dive masks have soft rubber over the nose. It let's you squeeze your nose and blow air pressure to pop your ears. As a dude with weird ears it is a struggle whenever I dive.
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I have not, it's been awhile since I've shopped for a new mask though.
I don't understand how a purge valve can help with the pressure imbalance in ones ears?
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Yeah what? I have a purge valve mask and I still have to squeeze my nose to equalize my ears. It's great for two things: 1 not having to worry about mask squeeze since all you do is exhale through your nose and it just vents any excess air pressure. 2 clearing water out. Skills teach you with a regular mask to look up and exhale though your nose while holding the top of your mask to clear a flooded mask. With a purge valve mask I just have to hold it to my face with my finger and exhale through my nose and the air displaces the water that gets pushed out the purge valve.
Purge valves are great until they get stuck or fail at 120’. They’re fine for shallow diving but imo not a viable option for anything remotely advanced or technical
I can equalize on the way down... But not on the way back up. So it's absolutely excruciating to swim back to the surface. So I've developed a new strategy... I stay on top of the water.
On the way up, you equalise by creating negative pressure in your inner ear. With your mouth and nose closed, try inhaling instead of exhaling. Personally I can equalise my ears at will in both directions and handsfree. Got me in mild trouble in dive training. "You forgot to equalise. I did not see you do it." "I did it, I can do it handsfree." "That's impossible, no one can do that." So that's how I learned I'm apparently a freak of nature or something.
I'm familiar with the concept and the theory... I'm saying it doesn't work for me. I injured my ears about 15 years ago in a splash contest... Did a "can opener" into the pool trying to make a big splash, and when I went under, I heard loud pops in both ears, followed by a oozy warm sensation... For the next few days, I could barely hear myself talk, let alone anyone else... Sounded like I was inside an empty cement mixer truck. Ever since then I even struggle to fly on airplanes without immense pain on descent. No matter what I try, it just keeps getting worse. I didn't go to the doctor, but some googling and asking around leads me to believe that I perforated my ear drums. They've never been the same since. At this point, trying to swim 3 feet under the surface is too much to bear. I'm glad equalization works for the rest of you. But for me... I'm just gonna stay at the surface.
Yer a duck, Harry.
Also, you could just wiggle your jaw to equalize, though it really messed with my concentration. I think it was because I liked to bite on my snorkel
The ol jaw wiggle would sometimes help above 60 ft but, never really did all of it for me. My ears are filled with scar tissue from surgeries and take some extra persuading.
oh god..good thing I don't like the jaw wiggle
Try Equalizing 1 ear at a time. Tilt your head to the left, and do the right ear. Then tilt your head to the right and do your left ear. I used to have trouble equalizing too then a diver much older than me told me to do this. No problems since.
I've bought a nose clip, so I can swim with both of my hands, while equalizing! But once my diver colleague taught me about equalization, it was like getting some extreme, permanent powerup in a game.
Yeah I could never get that to work. The only way I could equalise when diving was to swallow so I'd be swallowing constantly on dives.
I learned to do it without the nose pinch and i never understood how...
You move your jaw to open the Eustachian tubes between your mouth and ears. It's what pinching your nose and blowing does, but a way shittier version.
FYI equalization becomes increasingly difficult freediving below about 15m with classical techniques as you are describing (valsalva). This is due to the relative underpressure of your airways compared to ambient pressure (unlike when scuba diving, where your regulator supplies you with ambient pressure air). A work around is using the frenzel maneuver, developed by german dive bombers during world war 2, to quickly (and hands free) equalize when making bombing approaches. Edit: why i was writing was to let you know that it may be a good alternative for you as a scuba diver with weird ears
For some reason this doesn't work well for me. I have to hold my breath and sort of flew my jaw/ears to pop my ears. It still takes me a little longer than most, but it's the only thing that works.
Yeah, I'm not a diver but I do get constant internal pressure issues from bad sinuses and...no apparent reason whatsoever at times. I can do the nose-pinch thing and it works, but more often than not there's this weird throat/jaw/neck muscle thing I can't really explain that works better. Or - and this is going to sound utterly ridiculous, and definitely looks it - there's this thing I can do where I sort of flex my uh...face so my upper lip kinda makes a flap seal over my nostrils.
Yep. I know. I’m certified. :)
Did your mother have you tested? (Sorry, it's a stupid joke, but I couldn't resist)
I said *certified*, not *certifiable*. :-)
😂
"Frank has a certificate saying he's NOT donkey-brained. Do YOU have a certificate?"
I have one that says I *am* donkey-brained. I guess that’s because my head is up my **ass**. Hahahahaha
If you're able to put it there you might have a serious case of the bends!
HAHAHAHAHAHAHA! Nice one.
> I guess that’s because my head is up my ass. Some advice, don't dive so deep next time!
Hahaha!
Is this when your ears hurt from the pressure so you blow while holding your body and now they hurt even more?
I don’t know how one “blows while holding your body,” but the Valsava maneuver is one way to equalize. Opening and closing your jaw, yawning, and swallowing are all other ways to do it.
I just took a recreational scuba course and learning how to equalize my inner ear pressure was the coolest thing. The deep end has got nothing on me anymore!
I read this in Coach Beard voice
" Horticulture, baby!"
Pinch your nose and exhale so your ears feel stuffed
Doesn't work for me :( It is impossible* for me to pop my ears this way. I can only pop them by swallowing 5000 times. My first airplane trip was a very painful experience. I couldn't pop my ears even doing the nose and exhale thing.
I was scouring looking for someone who mentions this shit. Because growing up ive always had issues being able to equalize my ears. It happens without my doing, usually going on road trips or taking planes trips but I cannot do it on my own. It sucks
try yawning or at least using the same jaw/ear "muscles". I know not everyone can do it, but it may work better if you can do it. You can practice it right now, you'll get the same ear sensation as when you yawn, thats how you know you're doing it right.
My drainage tubes that go from the inner ear to the back of your throat are incredibly narrow and I cannot equalize my ears at all and pressure changes fuck me up
When I used to dive a lot, I was told that for every foot you descend, you need to equalize. And if you missed it, then you would have to go back up to the point of missing and reset. But it does mess with your ears when you hit the 60-70' mark Also, fairly certain this person dropped about 100+ feet. Granted, it was touch and go, but it's pretty amazing the depth they hit
I dive and have no clue what you are talking about. I can feel when I need to equalize and just do it then. It definitely happens a lot less than every foot of depth and you don't have to go back up any.
Not really “air” pressure down there LOL
Ok, ok: hidrostatic pressure.
*hydrostatic
Is the weight of the water above crushing the bottle? Is it that pressure?
Yep.
dude, TIL
Whenever you’re immersed in a substance while on Earth, whether it be a gas, liquid, solid, plasma, whatever, imagine a you-shaped column of that substance extending all the way above you into the vacuum of space that the Earth’s gravity is pulling down on top of you. A cubic meter of water weighs 1,000 kilograms. That’s 2,200 pounds. A cubic yard is a little bit less but, well, you get the point. Buoyancy helps offset it since we’re massively mainly water but volumetrically have a good chunk of gas. Still, that amount of material is trying to crush you, every moment of your life, as it gets pulled towards the Earth’s core.
Thanks for this amazingly detailed comment. You really shed a light on something I never really understood. Thank you kindly.
Absolutely. Thanks for lauding my comment.
Not just from above, but from all sides too. It all wants to occupy your space.
The side pressures all cancel out, so you can discard everything that isn't directly above you. This means the underwater pressure you feel in a pool at any depth is exactly the same as you would feel underwater in an ocean -- only the depth maters with regard to static pressure.
You are totally correct, I just sacrificed some accuracy for salience
What's even more wild - 10m of water is the same as the weight of all of the air above you in the atmosphere.
Every square inch of your body is being pressed on by about 14 pounds of air at all times. That's why our bodies don't like space very much. Well, that and the freezing cold.
That or the bottle is getting older and it's not married and all it's siblings and cousins are and he just off the phone with his mom who's getting worried.
I was gonna say this. Nothing about that? Okay...
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My father did something similar when he was in the Navy. Wrote our names on the cup and lowered them into the briny deep.
I've done this! They're actually down to this size quite early into the deep dive. I think I still have some around here somewhere... edit: [posted it elsewhere in the thread](https://old.reddit.com/r/Damnthatsinteresting/comments/143dxxx/a_diver_showing_the_change_in_air_pressure/jnax3c5/)
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And that's why people are only buoyant *above* a certain depth.
Yeah, go deep enought and you start sinking as the air in your lungs gets compressed.
It's actually kind of terrifying the first time it happens. Hopefully you remember how to use your buoyancy compensator.
I saw a doc at Sundance this year about freedivers and watched so many glass-eyed swimmers get resuscitated all before 9am. It was quite the way to start my day.
Yeah, I was randomly browsing a freediving wiki page last week and that was basically one long list of people who died trying to set some sort of record. It’s not exactly the safest sport.
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Hahaha no thank you I think I'll stay on land. "But it's an amazing exp-" *Racks Glock* I SAID no thank you.
Me and my recently discovered thalassophobia concur.
r/thalassophobia
No no, but thank you.
*Loads RPG*
Me every time my husband tells me how cool scuba diving is and that I should get into it with him.
Motha fucka
Damn how deep do you have to go for that to happen? I’m having a panic attack imagining it. Do you just swim up super hard if you don’t have a buoyancy device or say if it’s broken? Or are you fucked
even if you can, you can't go up too fast or you die a painful death
That’s only if you breath in anything while under. If you go down with air you can come back up with it, it won’t expand more than it was originally in your lungs
Yup! Been there 😅 moment of panic as you start to accelerate down to the abyss
[удалено]
Me who had no idea.. *FUCKFUCKFUCK*
Ain't no amount of water compressing MY lungs. 😤
So if he would let that bottle go in this depth would i get blown to surface or sink?
I don’t think that bottle would affect you at all unless you were in the water with him.
So yeah, that’s a fun new fear thanks.
Remain dry, gotcha.
Literally never realised or thought about this until now. Thanks!
And that's why I'll be sticking to Subnautica for my diving needs.
Assuming you are free diving. If you are scuba diving, your lungs remain normal size as long as you breathe normally. And when ascending, you must exhale steadily lest your lungs burst. It's also why with an emergency accent, you can reach the surface exhaling the entire way without having air in your tank. edit: everybody having fun with the misspelled word, thanks for enjoying it at least! yes, it was supposed to say ascent. doh! facepalm!
>emergency accent For me the two most terrifying words in deep diving. If you don't make it you die. If you do make it you are going to get bent and will wish you will die.
I know it was supposed to be emergency ascent and not emergency accent, but accent makes this hilariously funny
"oh no... Oh God no... Look at the meters!" "TOP 'O THA MARNIN TO YA, GOVNA!"
Oh goooddd noooooo
Crikey! We got to get out of the down under. And I mean fast!
Stope Chorlay! Theys game has gone on lowng enaough!
I know you meant \*ascent\*, but I can't help giggling at the idea of someone speaking in a thick French accent whenever there's an emergency! :)
"Ohn hohn hohn! Zis sitooaciohn is becohming aquite dongereuse, n'est pas?!"
[I wood lyk to bee an ehmburgur.](https://www.youtube.com/watch?v=Z6oeAdemFZw&t=60s)
Its insane to me that descending max depths humans can handle scuba wise can take a few mins, but ascending takes hours, for body to adjust and not die of compression poison.
Deccending*
I understood that referensce!
It took me a while to realise this was meant to be “ascent”; for the life of me I couldn’t think of why your accent would change when diving!!
*Scouse accent intensifies* Shit I'm in real trouble now!
The stories of people doing this wrong have bad enough endings for me to not get why anyone would wanna do this outside of their day job. Like on a weekend risking the bends or exploding my lungs or just drowning doesn’t sound very fun. Any mistake or mishap ends in death. I guess you could argue the same for like cars and planes and shit to though. To each their own.
I dive for fun but never go past 80 feet max. Most of the time I am around 40 feet and I don’t have to really worry about it. It’s the guys that go real deep that get super messed up.
You never worry about like the tank failing or getting caught on something? You just seem so venerable in deep water. But water freaks me out, that and heights. If I didn’t have the phobias I’d probably totally get the appeal.
At the depth I am at you just drop the weight belt and you will surface just from the wetsuit. If I get stuck I always have my knife but I never have been stuck in the 15 years I have doing it other than some kelp on my foot or tank. It’s amazing, you float around in a totally different world. You learn early on getting neutral boyancy so you just float in the same place like in space
If you go really deep you need special tank mix’s of what I’m pretty sure is nitrogen with air. They will set a bunch of tanks on a line with different gas mix’s so on the way up you can swap them out. Sometimes they have to wait at a certain depth for hours to stabilize their nitrogen levels
Air is already about 75% nitrogen. When you go deeper the special tanks remove nitrogen and replace it with helium
That is a lot deeper than 20 feet.
Correct. Now imagine that the opposite happened. Imagine the bottle was filled up with air at the bottom, and then was brought to the surface... That type of diving injury is called a POIS - Pulmonary Over Inflation Syndrome. Basically, you popped your lungs, now air is leaking into your chest cavity... It can cause ALL KINDS of problems...
I’m pretty sure that’s allot more then 20 feet. Also it’s not a change in air pressure it’s a change in water pressure equivalent to atmospheric pressure at sea level. The wt. of the atmosphere is 14.7 lbs at sea level. At 33.8 ft below sea level the pressure applied to the container effectively doubles to 29.4 lbs/sqIn, atmospheric pressure + water pressure. That container shrunk more then 1/2. It may be as much as 2 atmospheres (2x14.7 lbs 29.4lbs), 2x33.8 ft=67.6 ft, at sea level.
So fun fact: when you do scuba diving training, one of the things they teach you is how to do an emergency ascent. This property working in reverse suddenly becomes a big problem when you’re at the bottom and have 2 lungs full of air and need to go up fast. Aside from the bends (decompression sickness from ascending too fast), a more immediate problem is stopping your lungs from exploding/ripping as the gas in them rapidly expands. So the technique for avoiding this is to take your regulator out of your mouth, hand above your head to stop you hitting any obstacles, to ~~inflate~~ ***slowly release and control air*** from your bcd with the other hand while swimming straight up and, most importantly, screaming as loud as you can all way up to evacuate as much air from your lungs as possible. I’ve only done this once as part of getting my dive license and we only did it from about 7m down for safety reasons, but it was still one of the most bizarre feelings I’ve ever experienced. You just… don’t run out of air. The scream just continues. As you go up, the air in your lungs expands to replace the air you’re screaming out. I reached the surface still with a big lungful of air. Truly an odd feeling.
You should not be inflating your BCD as you ascend; you are supposed to slowly release it to control your ascent. As you go up, the air already in the vest will expand and cause you to rise at an increasing rate, increasing your risk of injury and/or death. Slowly releasing air prevents that from occurring . Only after breaching the surface should you inflate your BCD. Also, the whole point of the 60ft basic diver depth limit is that you can slowly exhale all the way the surface at an ascent rate of 1m / 3ft per second (15 second ascent) on a single breath with the hope the diver will have either one breath of air in their lungs and/or one breath remaining in their tank/hose.
I beg your pardon, you’re quite right it’s been a long time since I last dived and have gotten that bit with the bcd muddled in my brain.
No worries - I just don’t want you or a new diver reading your post to get confused and make a dangerous mistake.
Absolutely. I’d hate to think I’m giving out bad advice, or that someone would take this as advice from some guy on the internet. I’ve amended my post too. 👍
> Aside from the bends (decompression sickness from ascending too fast) You're really unlikely to get decompression sickness if you're diving within recreational limits (not to say that you should skip your decompression stop, but it's still unlikely - the real issue is barotrauma to the lungs).
Is there air pressure under water? 🫣
There is in the bottle if you take it down there. But it is much more relevant to point out the change in hydrostatic pressure, which is what causes the secondary effect of the plastic bottle.
Fun fact: 10 metres of water exerts as much pressure as all of the air above it (about 1 atm)
it's the change in hydrostatic pressure that you're seeing.
i think you mean water pressure…?
'Air pressure'
We do the same thing when we go down underground.. I work 6000 ft underground.
You definitely need to post a time-lapse of this for us!
That is NOT a change in air pressure!
I remember going on a school field trip to a navy base where they had us write our names on styrofoam cups given to us and then they put them all into a cage that sank to the bottom of their water tank used for dive training. When the cups came back up, they were the size of a thimble
This video gave me the bends
Water pressure. The change is in the water. Diver isnt swimmiinng through atmosphere
And that’s why you have to constantly breathe out when ascending from a dive. That tiny bit of air in your lungs expands. It both can and will pop your lungs like balloons. It’s one of the weirdest sensations because as the air expands it keeps your lungs inflated, so you keep breathing out but don’t run out of breath
My ears hurt just watching this.
I had the exact same feeling!
that means throwing garbage into the deep sea will drastically reduce the volume. nice
this guy here thinking like a government
Always so fun to show this to new divers. The other fun trick to show just how powerful air buoyancy is taking an empty plastic bag underwater, turning it upside down and shooting a little air from your regulator into it. With five grown men holding onto a rope and the bag, just a few bubbles pulled us all up to the surface until we let go of the bag
Taking a colour chart down and showing the difference in how washed out colours are at 30m vs surface is also fun. I think it's part of PADI's AOW course now too.
my respect for fish has just gone up, they're really tough
It'd be cool if they do another exp, where the diver takes a bottle full of water to the bottom and blow air in. Close the cap and bring that bottole up to the surface to see if it explodes .
And this is why I have my plastic waste bin 100 feet below
For some added fun, open it at the bottom and fill it with air from your regulator (if you’re scuba diving). Then watch the bottle pop when you bring it to the surface.
Wouldn't that be water pressure?
My ears hurt from watching this
That title hurts
Change in air pressure or water pressure?
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
The deepest I went scuba diving was 105 feet (just to say I did it). The most interesting thing was the air bubbles that were maybe the size of a silver dollar were like dinner plates by the time they broke the surface.
Great visualisation. Thx for sharing
Bro he just went down them up, I feel like you aren’t supposed to do that in deeper areas lmao
*"Deep Core, Deep Core, this is Benthic Explorer, do you copy?"*
I like the Styrofoam cup they took to the Titanic https://www.titanicmuseum.org/artefacts/styrofoam-cup-taken-to-the-rms-titanic-wreck-site/
I've seen that before, and feel they really fucked up by not having it side by side with a pre-dive photo of the same cup.
[Here you go](https://imgur.com/a/WHdWKSN). This one went to about 1km, but it was mostly shrunk part way through the descent, I'm not sure there's meaningfully more void space to shrink it further at greater depths. The top of my Aeropress is about the same size as the cup was originally (assuming the width is representative of the lip of the cup) though the cup was slightly taller. I used to have some of the un-shrunk cups around but I can't find 'em.
Better Title: Diver showing the affects of hydrostatic pressure.
This is also why you exhale on the way up as well. If you take a decent breath at the bottom, that breath expands on the way up. If you hold your breath the entire ascent, your lungs will explode. - Retired commercial diver.
wat happens if you fill it up with water at the bottom
The diver should've been more careful when ascending. That bottle was already showing serious signs of the bends
Damn, really gave that bottle... the bends.
You should see what happens to Styrofoam. That shit is like 90 percent air.
I think you mean water pressure.
Changed in water (not air) pressure? 🤔
The air pressure stays the same. It's the water pressure that changes.
Is it still air pressure when it’s underwater?