When the USS Scorpion was lost in 1968, when she reached crush depth, her reactor and propeller shaft imploded into her bow like a collapsable telescope in about 10-30 milliseconds (I think it was closer to 10 milliseconds)
It was less time than it takes for the human brain to process input from the senses which I believe is about 150 milliseconds tops.
Mercifully, which means they had no idea.
I don’t understand how the air could heat to the surface of the sun before it imploded. I would think that alone would vaporize anybody in it before it did. I would think the worst nightmare would be in a sub with no way to get out as it fills with water like that movie “The Abyss” where they can’t get the door open and the Captain has to watch them drown.