In my last post, I'm confused how drwls got P2/P1 = 14.8

Answer 1

I calculated the pressure at sea level (P1) and at the depth (P2), and divided them to get P2/P1.

P2 = P1 + (P2-P1)

P1 = 1.013*10^5 N/m^2
(I may have used a slightly different number)

P2 - P1 comes from the equation
P2 - P1 = (water density)* g *(depth)