I think to get (or I should say, to keep) the right atmosphere, sound will also be very important. Looking at that last picture you can almost hear those typical underwater submarine "clunk, clunk, dzing, blooop blooop" sounds. If you know what I mean ;). (Not completely sure about the "dzing".) Have you seen "Das Boot", a movie like that should be a great source of information and inspiration!
I just found a great collection of submarine sounds like alarms and radar bleeps! Here:
http://www.steel.sakura.ne.jp/contents/sound/e_sound.html
(I don't know about copyrights but there is an e-mail address on the "home" page. Not recently updated though it seems.)
I just found a great collection of submarine sounds like alarms and radar bleeps! Here:
http://www.steel.sakura.ne.jp/contents/sound/e_sound.html
(I don't know about copyrights but there is an e-mail address on the "home" page. Not recently updated though it seems.)