wwii fleet boats periscope depth was 60 feet.
radar depth 50 feet.
subs don't fight on the surface and expect to live very long, so, lets not do that.
it's what you'd do if you were planning a submerged torpedo attack run.
But
there needs to be some surface traffic to shoot at.
Sonar has not reported any contacts.
Radar can't be used underwater.
Raise the scope and look around, then surface is all we're really doing.
Nothing to shoot at.