[A Very Super Market]

Hm... in early way, you could run surfaced and dive when only when attacked. But when RADAR is developed, the captains learned that they were only marginally safe during the night. Daytime became extremely hazardous as the war progressed and new airbases and new aircradt became operational. Eventually, even surfacing at night became dangerous, aircraft could be completely guided by RADAR.

But thats the Atlantic

The axis powers never had RADAR or anything, so allied subs could operate surfaced a lot. But the Pacific was swarming with planes, and the water is fairly clear, so the US submarine captains would also dive during the day, but only when it was deemed dangerous to be exposed