In the beginning of the movie 'The Imitation Game' there]s an impressive shot where the camera lens (the viewers perspective) flies past war planes in the air and war ships at sea and dives underwater to a U-Boat Wolf Pack and through the hull of a sub, through the passageway to the radio operator dutifully tapping away, sending a (coded)signal.
The inside of the U-Boat is lite with red lighting. But the sub is underwater.
Is this a poetic license on the part of the film-makers or did U-Boats travel underwater with Red lighting?