Clearer thought experiments concerning the PSI...
...Not that your lily really needed gilding, Tony. But this is fun!
Climb down a 15 foot ladder - feel your ears popping?
Swim down 15 feet underwater - compare feeling on ears.
Have a friend bury you under under 15 feet of bricks (say farewell to friend, first).
Or if you want something you can measure:
Stack 15 feet of bricks underwater. Drain water away and measure how your stack of bricks has expanded to be 16 feet tall!!!