this post was submitted on 19 Apr 2024
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Science Memes

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[–] notapantsday@lemmy.world 57 points 6 months ago (2 children)

You can go much deeper than 10 fathoms without supplemental oxygen, half the people reading this right now could do it with some training.

The world record is 117 fathoms on a single breath.

[–] Kecessa@sh.itjust.works 38 points 6 months ago (1 children)

Free divers are a bit crazy...

[–] wahming@monyet.cc 32 points 6 months ago

No, just brain damaged from oxygen deprivation

[–] Karyoplasma@discuss.tchncs.de 1 points 6 months ago (1 children)

How do they go back to the surface without fainting from decompression?

[–] notapantsday@lemmy.world 4 points 6 months ago

They're only down there for a very short time and they don't have a lot of nitrogen stored in their lungs, so decompression sickness is usually not an issue. I think there have been a few cases, especially with repeated, very deep dives. But nothing you have to worry about as a normal hobby freediver.

Passing out at the surface is quite common though, but not due to decompression sickness. It's the lack of oxygen that can happen when you have learned to completely ignore your urge to breathe and then stay down for too long. The reason why you pass out at the surface and almost never at the bottom, is because the water pressure compresses the air in your lungs. At a depth of 10 meters (30 feet), four liters of air in your lungs are compressed down to two liters. This is basically "concentrated air", which contains "concentrated oxygen". If the air is compressed to half the volume, it's like having twice as much oxygen in it. Then, as you ascend to the surface, the air in your lungs expands again, turning the concentrated oxygen into regular oxygen and then it's just not enough anymore and you pass out.

That's why it's recommended to always have someone with you who stays at at the surface and who can step in if you pass out, keeping your head above the water. It has never happened to me, but I'm really a beginner and I still have an urge to breathe that forces me to go back to the surface after a short while.

[–] svc@lemmy.frozeninferno.xyz 29 points 6 months ago (1 children)

I need supplemental oxygen at less than 1 fathom under water, if I stay there long enough...

[–] raspberriesareyummy@lemmy.world 12 points 6 months ago (1 children)

I highly recommend using compressed air over oxygen. Nitrox 100 (pure oxygen) becomes toxic below 5 meters...

1.6 bars partial pressure Oxygen is considered unsafe / hazardous.

[–] anton@lemmy.blahaj.zone 7 points 6 months ago (1 children)

Nitrogen also becomes toxic, requiring you to substitute it with helium (or hydrogen).
Interesting talk on the subject: https://youtu.be/skL5EQa8DFY

[–] raspberriesareyummy@lemmy.world 3 points 6 months ago (1 children)

It's why I'll always remain happy with recreational diving at depths less than 40m :) Tech divers are a bit crazy imo. Sure, there's nice views to be had (if you bring a lot of light), but it's not worth the risk for me.

[–] Zehzin@lemmy.world 29 points 6 months ago (1 children)

While we're at it, 20000 leagues under the sea is the distance they travelled, not the depth

[–] Dabundis@lemmy.world 13 points 6 months ago

For scale, 20,000 leagues is almost 9 times the diameter of the Earth

[–] Rolando@lemmy.world 19 points 6 months ago (2 children)

How many fathoms do you have to go before even death may die?

[–] MelastSB@sh.itjust.works 20 points 6 months ago

You're thinking of eons, which stand for time. But I like where your head's at

[–] technohacker@programming.dev 10 points 6 months ago (1 children)
[–] TransplantedSconie@lemm.ee 3 points 6 months ago

"Dammit, monster! Get off my lawn! I ain't giving you no tree-fitty!" It said, "How about just two-fitty?" I said, "Oh, now it's only two-fitty!! What?! Is there a sale on Loch Ness munchies or something?!"

[–] Klear@sh.itjust.works 14 points 6 months ago (2 children)

1 fathom = 1.8288 metres. Yeah, I get why it's funny now.

[–] zaphod@sopuli.xyz 5 points 6 months ago (1 children)

What's so funny about 1.8288m? I don't get it.

[–] funkless_eck@sh.itjust.works 7 points 6 months ago (1 children)

your mom and I 1.8288m'd last night

[–] drislands@lemmy.world 2 points 6 months ago

I can't fathom how you'd find that funny.

[–] captainlezbian@lemmy.world 4 points 6 months ago

And for people who don’t know how big that is. It’s about the height of a slightly tall man

[–] mo_lave@reddthat.com 13 points 6 months ago

Unfathomably based

[–] Aussiemandeus@aussie.zone 5 points 6 months ago

The end of that reads like the grim dark of the 40k universe there is nothing but war

[–] SeabassDan@lemmy.world 4 points 6 months ago

I read that as Just Poised on Things and thought it was very fitting.

[–] PhlubbaDubba@lemm.ee -3 points 6 months ago

And then some nerds with a cool camera robot get down there because they want to poke dead whales with shit and see what happens