You sound like someone who can answer a couple of questions. The sub surfaced, so why didn’t they send out their coordinates while communications were still up and remain at that location until rescued? Don’t subs naturally float but have to be forced to go underwater?
IDK. The only reason they wouldn’t have been able to stay on the surface would be flooding. Maybe they lost all electrical but they would have some kind of emergency battery and communications off of that. I think they sank. I hope not.
Rode subs for three years.