A malfunction resulting in loss of steerage and/or propulsion can cause the boat to drop below crush depth, resulting in greater external hydrostatic pressure on the hull than the boat's internal atmosphere. Material can be thrown off from a non-solid object but this does not necessarily happen and if the pressure differential is sufficient, the imploding structure is/can be changed to a more compressed, denser, or even different material, much like a star collapsing of it's own gravity and becoming a neutron star. The event is instantaneous with respect to the crew and they indeed did not suffer if this was the case.

[link:https://www.democraticunderground.com/10141935908|

I was involved with submarines during my time in the U.S. Navy so this is of particular interest to me. I have little doubt that an implosion of the San Juan is what happened and I extend my sincerest sympathies to families and friends of the lost mariners, my brothers and sisters in arms beneath the sea.

After reading the comments in this thread, and the linked thread, it sounds as if they just may be vanished so quickly from the experience there wouldn't have been time to be conscious of their circumstances.

Surely hope that's the way it went.

What a monstrous tragedy.

Thanks for the information.

....the bad being the flash-fire they all died in as the hull imploded and heated up the air as it compressed it. (but almost instantaneously)

Also they would have had a bad last 5 to 10+ mins as the out of control sub sank to crush depth assuming they were any conscious crew-members. They'd know they were out of compressed air to blow the tanks or had gotten too heavy to rise without propulsion or whatever other issues they were having and a crewmen would be reading out the depths to the Captain (or whoever was in charge at this point assuming the remaining crew weren't all involved in damage control) and they all know what the sub is depth rated to. When new she was taken to a test depth of 980ft/300m which means I'd guess a crush depth of between 1300ft and 1800ft somewhere. This sub being 34 years old she imploded in the 1200ft range I'd guess but they would have heard the end building as the hull groaned and compressed and things started breaking while the crewmen calmly goes "Ahora pasando 400 metros.." They'd all know they had seconds to live at that point.

No bueno. Scary end.