Some good suggestions and hope they are considered. In addition to what has already been suggested I'd like the following to see the following...
* Water leaking into the sub, it's too dry in there even when not damaged.
* On crash dive, we need to see the crew running forward.
* Along the lines of the Wolfpack, player should be able to coordinate convoy attacks with other subs, perhaps by mission orders or by selecting and/or responding to attack options via direct radio contact with other sub.
* During rough weather and only on very
very rare ocassions I think it would be hysterically appropriate to see somebody hurling b/c they are sea sick!

Oh, and on a calm day it would be great to see a crew member taking a wizz off the boat.
Oh yeah, one of the things w/ SH3 that has confused me that might need to be considered....
* You shouldn't be able to take in the fish from external storage in rough weather.
* Fatally wounded crew members are moved around the sub in the crew management screen....did they really carry the corpse around?????
That's all I can come up with right now, lots of good ideas here, hope the right people are taking notes! :|\