Talk:Depth Levels/@comment-27658215-20160122224315/@comment-24.96.17.64-20160422064417

As an avid diver, I am actually appalled at the information being spewed here on the subject, and you all talk like you actually know something about it. I don't know where you guys get your information but not a single thing written here is true. Oxygen narcosis? Using less oxygen at depth? Cylinder air compressing with depth but the air that is breathed stays the same? All of this is absolutely ridiculous and not only does it defy the basic laws of physics, it is also obvious that not one of you has ever even been near a scuba diver in your entire life. If anyone conducted a dive based on any of the information here they would likely kill themselves.

The air in a tank is at whatever pressure is dictated by PV=NRT. Since the walls are rigid, this is not effected by depth. Your regulator takes this high pressure air and converts it to AMBIENT pressure when you inhale. So the deeper you go, the greater the ambient pressure and thus the more condensed every breath is. The pressure in the tank only depletes based on the amount of air you have consumed. So the deeper you go, the faster you deplete your tank as you breathe. This is somewhat poorly represented in the game, but it is the only aspect of open-circuit diving that is actually represented in the game at all.

But breathing gas that is at high ambient pressures (which is quite high when you are very deep) presents a host of other problems. Since you are breathing gas at a higher pressure, you can get nitrogen narcosis, which disorients you and makes you stupid (which is dangerous underwater.)  Gas also begins to dissolve into your tissues, and as you come up, that gas fizzes out of your tissues like the fizz in a soda when you open it. Too much fizz and you choke your blood vessels with bubbles and get bent, which can cause you to be permanently crippled, brain damaged, or dead. Oxygen is also toxic at high pressures, pure oxygen can only be breathed at a depth of about 20 feet before it is toxic. Regular air can be breathed down to about 200 feet (not using exact numbers and everyone has different tolerances) before the diver starts to be at risk of oxygen toxicity. When a diver has a oxtox hit, he essentially has a siezure and drowns, and it can happen with no warning.

This is why divers going deep often carry many bottles containing various mixtures of oxygen, helium, and nitrogen to breathe at different depths to avoid these problems at different times during the dive. Rebreathers can negate a lot of these effects or minimize them by precisely controlling the mixures of gas that you are breathing, varying the helium, oxygen, and nitrogen precisely depending on depth and whether you are on-gassing or off-gassing.

Honestly the most "believable" way that a human could swim as deep as you swim in the game, without a pressurized suit (exo suit) to provide normal surface pressure inside the suit, would be some futuristic device that scrubs the blood of carbon dioxide and oxygenates it without the diver ever needing to breathe. Something like a small portable dialysis machine that has a really high flow rate of blood.