Das Boot was what stirred my interest in submarines.
I expect you are aware, but I was surprised to learn recently that the actual lead engineer on U 96, who was a central character in the series, is still alive.
Although he declined any involvement in the filming, at the venerable age of 103, Mr. Friedrich Grade is now providing his unique insight toward the development of the sub sim Crush Depth, which will be epic if it sees fruition.
https://www.warhistoryonline.com/ins...-das-boot.html