I didn't know whether to cry or laugh.
But, if you want to see what it was like. I can sorta do it on command now. Next time you climb down the hatch and order periscope depth.. get off the ladder and immediately hit Shift+U to teleport. Since the sub is not under yet, it will teleport you back to the bridge, but the sub is still going under.
Now you can walk around the deck at periscope depth. You'll have to surface though to get back in.
Might be a cool trick for a movie maker.