Submarine needs windows and headlights to see where the heck they are going duhhhhhhhh Who woulda thunk it?
Long time ago on a nuclear submarine, the captain told us (under certain conditions) that we OOD's should raise a periscope for practice.
I can tell you even years later that you can't see much more than almost nothing, even on a sunny day, when just a few rays make it down to even a shallow depth.
As to the people who keep asking about sonar, we carry both active and passive sonar systems but active is not used (almost never). Passive sonar is NOT going to "hear" a mountain.
Exactly. The Seaview would never be so blind.