Nothing says every situation is survivable. In the situation you propose, there are many factors weighing against a successful outcome. We haven't even discussed the high likelihood of fatal outcomes simply due to the very cold water temperature - one source I consulted mentioned death occurring within five to ten minutes in 30ish degree water in many (not all!) subjects.

A lot of uncontrollable variables at play and definitely no recommended, "safe" solution. A worthwhile subject that has generated constructive posts.

I would not want to be in a submerged vehicle 80 feet deep, struggling to get out of the vehicle. i would definitely be in over my head, as they say....
Geezer in Chief