[dannybuoy]

It also would make the surface protocol 1 step easier, and you'd have more time to do it. And, in case something does go wrong, it makes it easier for the safety divers to do what they have to do.

But the main idea is that the added stress and discomfort of diving without a mask, plus the greater exposure to water on areas crucial to dive response, causes the body to conserve oxygen better?

Oh wait, mumbo jumbo territory.