Same here, lots of needless drama but tons of respect for those who just get after it (the gold). I know they aren't that deep but they do stay down quite some time. Didn't they say 4 hours. If they had to surface too fast from much of a depth wouldn't they be in a world of hurt?
I am a former scuba diver, and was a hard hat diver for six years. I was a medically certified hyperbaric chamber operator. I know of which I speak.
You are asking questions that have to do with different things. There are several things that can get you in trouble in diving. One of them is decompression, or the bends. Was first diagnosed during the building of the Brooklyn bridge by caisson workers who worked under pressure in the underwater caissons. Also called caisson's disease. Gases go into the blood, and when you come up, they come out of the blood in a predictable way depending on how long and how deep you dove.
There are no decompression limits, which is the point after which you need to decompress. It is based on bottom time and depth of dive. For 35' of water, a diver can spend 310 minutes according to the US Navy no decompression chart before needing to decompress. What that means is that rarely do any divers in the Nome area run into decompression problems unless they dive in water deeper than 33 feet. After that, all sorts of things can happen, and it gets complicated, but for the purpose of this discussion, we will not go there, because it is not relevant.
The other thing is simple expansion of air. If you fill a balloon underwater at 33', seal it, and let it go, it will expand exactly twice in volume when it reaches the surface. All bubbles grow as they rise. Holding one's breath after taking in ANY air underwater puts one in danger of air embolism. If you only have the air you take in on surface, as the one guy who filled his lungs, then free dove to get their gear back, he had no danger of embolizing because he only had as much air as his lungs would hold at surface pressure. It's called free diving, and the record is very deep, 300' or deeper, using weights, and lifting balloons, but no risk of embolism, because the diver can only take on as much air as his lungs can hold at the surface, not enough to expand and burst. Zeke, on the other hand, took in air underwater, then shot to the surface. What happens is that the air can overexpand, and go directly into the blood stream as big bubbles, killing you instantly. Zeke was at a lesser risk because his rig was out of air, so he probably didn't have an excess of air in his lungs enough to explode them. Or he exhaled coming up.
If you were sit on bottom in the three or four foot deep end of a swimming pool, fill your lungs with air from a scuba tank, hold your breath, and then shoot to the surface, you can embolize, and the air will go through your lung tissue into your blood instead of coming out your mouth. You would die if not put into a hyerbaric chamber within a couple of minutes.
Part of diving training is doing a "blow and go" from 33'. You are in full scuba gear at 33'. You take a breath of air. You remove your regulator, and head for the surface, exhaling the whole time. You never hold your breath during the ascent. There is no desire to inhale, as the air in your lungs is expanding as you come up, and you are just letting it out your nose and mouth. The problems come when one holds their breath.
If you ever take scuba lessons, probably the first thing they tell you is NEVER HOLD YOUR BREATH.
The Nome divers haven't run into much problems yet because they are staying well within the no decompression limits, so no bends, or need for hyperbaric chambers on site. I don't know about the barges that are running in waters deeper than 33'. When I was a commercial diver, we took a decompression chamber with us on dives in water of ten feet deep. That was so that if we embolized by holding our breath, we would have some slight chance of survival. I don't know if it was USCG required, and I wonder when USCG and OSHA will enter this cluster polka, probably after a few fatalities. We shall see as the circus goes on, and these inexperienced divers spend more time in the water if any of them run into embolism problems from breath holding, but as far as popping up from shallow depths, they have no problems from decompression bends. Just embolizing.
Hope this helps you to understand.