Uhh, Freon isn’t poison- it’s an oxygen displacer. May not be much to choose from, but those poor guys suffocated.
I have always had the feeling that my destiny was to be at sea on a sub, I have tons of books, novels and last year I built a 52” model of a Gato class US sub, thats a WW2 submarine that was one class before the one used in the movie with Cary Grant, the pink one.
My heart reaches out to fellow sailors with no animosity at all. The Russians have not had good luck these last few years with their naval forces.
I’m not sure how you define poison. I’ve been involved in a massive freon leak aboard a submarine, and it was handled as a “Poison Gas” event. Many of the crew inhaled enough of the freon to make them very sick. Fortunately, none of us died in the incident.