Most wire-guided torpedoes use two wire dispensers, one inside the torpedo exiting through the hollow prop hub, the other attached to the inside of the inner torpedo tube door. The obvious downside is that, once you've fired, you can't close the outer door until the torpedo gets where it's going.

A camera wouldn't help much. Sound travels through water a lot better than light, and at best you might be able to see twenty or thirty feet in crystal clear water -- which you probably wouldn't have.

"Down Periscope," curiously enough, is generally conceded to have got more right than most of the really "serious" submarine movies of the last few years. (Though there is one absolutely glaring error with Lauren Holly's uniform, and it does continue the usual movie convention that American fleet submarines had a periscope in the control room.) (At least they didn't sound the "surface" alarm to let everyone know they were diving.)

J.T. McDaniel