Of course, you need to deal with fast changes in pressure during the short journey towards the surface (protect your eardrums, lungs etc) and you may get decompression sickness depending on the dive time and avg depth at the moment of emergency, but hey, at least you're alive to deal with all those problems!
*: Generally, a scuba diver takes additional weights to counter the positive buoyancy effect of wetsuits, fat etc. These are mounted on belts or similar accessories that are designed to be very easy to get rid of in case of emergency.
This is not always true.
Your buoyancy decreases as you go deeper (and have more water above you, causing more downward pressure).
At a depth of 30 meters (100 feet), the pressure is 4 atmospheres, 4 times that of sea level.
Furthermore, not everyone is positively buoyant. The less fat one has, especially if not wearing diving suit, the more likely staying afloat/level to become harder.
As the depth increases, lungs and all bodily cavities shrink, further adding to one's density.
So, at 30 meters, it is actually quite a struggle to swim back up, even more so if you've lost your fins.
As for weights, I used to work out and exercise daily. During that time, I also dived few times a week spanning various sea conditions throughout the year and never have once taken weights as I was already negative.
Fast forward 2 years to today, I put on 15kg (33 lbs) and I need 10kg weight to enjoy my dive. But on the upside, I'd probably skyrocket to the surface if needed, lol :D
This statement is wrong on many levels. I'll try to correct just one part:
Your buoyancy must NOT decrease as you go deeper. That's one of the fundamental rules you need to follow if you want to dive more than once :) If you don't watch your depth and take necessary steps to maintain neutral buoyancy, you'd sink like a stone (or rise like a balloon). Nobody wants that.
What you mean is: you need more air in you buoyancy compensator (BC) to maintain neutral buoyancy (= keep your volume constant) as you go deeper.
If you don't take weights, you need to inflate your bc to lift you. In an emergency, you generally don't have time to swim up anyway.
All that said, I was just trying to point out that it was possible to "fall home" from underwater, assuming you are within the limits of your equipment.
A buoyancy compensator, filled with a fixed quantity (not volume) of air, does decrease in volume as you descend and the pressure increases. You'd sink faster and faster if you did not add air as required. Therefore, you must actively manage a BCD!
On the way up, the opposite happens. The quantity of air in your buoyancy compensator has an increasing volume of air as you rise and the pressure decreases, providing you with increasing buoyancy. Uncontrolled, this would rocket you towards the surface. Therefore, you must actively manage a BCD!
Lungs do not change in volume in SCUBA as they do when free (breath hold) diving, because your regulator is allowing you to constantly breathe air which is at the same pressure as the water around you.
When free diving, you carry weights to be neutrally buoyant at around 30 feet. Above the neutral buoyancy depth, you float towards the surface, and must swim down to descend. Below the neutral buoyancy depth, you become negatively buoyant, sink increasingly quickly, and must swim up to ascend. This is also important to be aware of; you don't want to strap weights to yourself that you can't drop: You may think you're capable of swimming up against your negative buoyancy, but if you only test at 10 feet under you may not be capable when you get deeper!
I did indeed neglect to explain what needs to happen. Thank you for clarifying. Let's all hope to enjoy many more dives :)
But also higher pressure pushing you upwards too! Buoyant force is equal to weight of displaced fluid, and so is independent of depth. (edit: given same fluid and temperature) (edit2: and well, buoyant force will be slightly stronger because fluid will be more compressed at the bottom)
Edit: Found a direct quote on wikipedia https://en.wikipedia.org/wiki/Properties_of_water#Compressib...: >The low compressibility of water means that even in the deep oceans at 4 km depth, where pressures are 40 MPa, there is only a 1.8% decrease in volume.[40]
Thank you for correcting this.
Near the surface it’s almost never an issue, but for ultra deep dives it’s important.
I'm not sure if it is just me, but I could not understand this at all. Do you mind rephrasing it? Which type of person has a harder time stating afloat?
The more fat one has, the less overall average density becomes, making it harder to sink. I have a close friend who is very overwheight and she can practically sit upright floating. I must admit I'd usually envy her when I struggled staying afloat while she enjoye a cool refreshment like it were her couch :)
So in short, less fat, more muscle mass, more bone mass harder to stay afloat.
Also the diving suite (which is made from a foam-like material) and some of the hallow diving gear make it harder to sink, hence the need for weights.
Bone + Muscle have specific gravities > 1.0.
Generally, the more fat on a person, the greater that person's buoyancy.
This is why saturation divers spend significant amounts of time in a pressure vessel after a period of diving to decompress.
This can't be the case here, they were inside their submarines the whole time.
ps: 100 feet = ~30m, 650 feet=~200m
Space is also open and visibility is great while in the depths there is no light and you can see only a few meters in any directions. Space also does not have "monsters" in it :).
> At least you can see past the end of your nose in space. In the deep ocean it’s truly pitch black.
Yup, I think it's the darkness and short distance visibility that makes for thalassophobia in most cases, at least it is for me. It scares me when I cannot see the ground, even when I know that it's only a few meters deep. However, I can stand on the top of a building and look down without any fear. BTW, I recommend r/thalassophobia.
> "Vertigo is something other than the fear of falling; it is the desire to fall -- against which, terrified, we defend ourselves."
That's from memory (over 20 years ago) but I think I got it right.
Your eyes tell you it's flat so you can step forward...but your sense of balance tell's you something different..brain is confused, you never have that feeling when your IN the wall.
I've thought maybe it's that things can come from below where as generally that doesn't happen on the ground. It could also be the reverb-y sounds. I have no idea. I love the ocean and swimming so ...
What terrifies me most is the stuff that lives down there [0].
[0] https://www.livescience.com/16231-creepy-deep-sea-creatures-...
No way man, didn't you watch Gravity [2013]? /s
If you come in at some super shallow angle you'd think you could do it, but at some point one ends up going from an orbit to a trajectory, at which point unless your air resistance can throttle your air speed below some value, you'll always over-heat?
That’s hardly rational though. After all, if anything goes wrong in the ocean, your buddies can just pull you up. If something goes wrong in space you drift into oblivion. If you are tethered in space and the safety rope breaks its game over. Just as if one was deep in the ocean without positive buoyancy.
And then space itself is all fun and games when in orbit around Earth. If, when facing the planet, you are feeling existentially terrified by there being simultaneously nothing and half of all of the Universe behind you then you can just turn around and have the safety of Earth at your back, at least.
But go deeper into space and that feeling of safety is gone forever. The same universal nothingness and everything-ness is in all directions. Space psychiatrists of the future may recommend we install permanent curtains to deal with this. Only those forced to work outside need experience the terror of the void.
At least you can see past the end of your nose in space. In the deep ocean it’s truly pitch black. Until the squids come.