Corrected entry: Just as Red October turns to port after engaging the caterpillar, the camera pans from Red October's stern to the Dallas, which is visible. In the next shot, Jones (the sonar operator) says Red October was some 4,000 yards dead ahead. From the previous shot of the two subs, they are less than 4,000 yards (or some 3.6 km) apart. The large distance would lead to zero visibility. (00:28:00 - 00:30:00)
Christoph Galuschka
24th Feb 2009
Correction: It's a movie convention to show visibility under water as much better than it actually is. A segment of shots showing nothing but black (or maybe some hull) would not be particularly exciting. Furthermore, showing the subs as they're supposed to be positioned is almost necessary to make the audience understand their relative positions and orientations, appreciate and see the action and achieve a dramatic effect.