Depth is no joke. I've seen some shallow blackouts by free divers in 15feet while lobstering.
I really do like having steel 100s @ 3500psi on my back when under.
Yeah, I can get to about 12ft and last about 3 seconds down there before I need to come back up. It kills my ears. (Thats how deep my pool is). About a year ago a screw came out of the drain cover and it took me an hour to get it back in because I could only go down in such short bursts to tighten it up; like 1/8 turn per attempt.
But I wonder if the barometer is already recording that data, but only Apple knows about it. I guess we will find out when people start running the diagnostics at the Genius Bar and pay attention. There is a barometer tab already.