What I am saying is that... If someone is lost in the woods, they are assumed alive.
That's not always correct. There are quite a few searches carried out where we know with reasonable certainty we are looking for bodies and not live people. A missing small aircraft is a good and rather common example of this, especially in the western US. We still risk our butts and the Civil Air Patrol loses someone about every other year in a search for a missing plane.
Another good example is the Alzheimer's patient who wonders away from home during the winter and is missing for two to three days. We continue the search even though the probability of survival is so low that it is a recovery operation beyond the first twelve hours. I use this second example because the last of several searches I took part in, was looking for the grandmother of a friend of mine.
The dive in question here that killed Sheck Exley was a dive to set a world record for depth. He was attempting to dive to 1000'. Sheck knew that this dive was an extremely high risk dive. That being said, anyone attempting to recover the body, had he not tied himself off to the guideline, would also be attempting a record depth (or near record), also likely to kill the rescuer.
I did not know the circumstances of his fatal dive. My assumption was that it was a normal wreck dive gone wrong. If that was the case and I was charged with leading the recovery, I would have advocated for the use of an ROV if one were available and the family was willing to pay for it. If he was really deep, then whomever went down to recover him needs to have his head examined.
As a former RCMP S&R diver had told me, if the body was deeper than around 100', after the gases caused the bodies to rise, they would expand on ascent, cause the body cavities containing the gasses to burst and then sink again, never coming back up. Bodies shallower, would generally come all the way up.
I can only speak of two cases where the water was >100 feet deep that I have been involved with. Both involved the same flooded quarry (which is now surrounded by a very tall fence and anyone caught on the property will go to jail) that is approximately 120' deep in the middle and in both cases the bodies were recovered several weeks after they went missing when they began to float.
Technically what you were told could be correct, but then again it is more likely that those bodies at greater depth tend to decompose at a slow enough rate (due to colder temperatures at depth) that they don't form enough gas at any given time to begin to float. Well, let me rephrase that.....at least not all the way to the surface...I've encountered one that was "hovering" a few feet off the bottom of a lake. That's the crap that haunts me to this day.
As for the rupturing of the body cavities, I can't say that is actually due to the gas pressure building up or changing as the body ascends. In the area was did dive recoveries in, we have a major problem with snapping turtles doing a considerable amount of damage to bodies that were down for any length of time so I would assume other areas would have a similar problem with anthrophagia which could explain the lack of floaters.
