[Sailor Steve]

Part of the reason for the night surface attack is that periscope lenses are too small to allow submerged attacks at night. Not enough light. If the game properly reflected that, and made it harder to spot surfaced u-boats in bad light, everybody's life would be a lot better.

It has been pointed out that in daylight destroyers can see just as well as submarines, but at night a black object lying close to the water has every advantage.