[Bill]

sciencemike
First let me make it clear that we agree on the ratio of partial pressures. My only observation is that by expressing the difference in reference to depth, you are understating the problem. No question that when you go from 10 meters to the surface, the PP changes in a ratio of 2 to 1. If you view that one way, it is a 50% decrease. If however you view it from the surface, where you end up, it changes from 200% to 100% and that isn't 50%.
Or is it??