Great read on how ILM made the shots. As a crew member on the USS Salt Lake City (SSN-716), we took many of the cast and crew out to sea for 24 hours before they made the movie to get a feel for what sub-life was like before they made the movie. All the cast and crew were great, and I think it made the movie better.
Actor Scott Glenn, who plays the Captain of Dallas, modeled his character after our Captain, Tom Fargo. https://www.youtube.com/watch?v=2rjO_VrESNo
It is a great movie!