I have the same nightmare atleast once or twice a week, where I run out of air while working(diving) and I'm to deep to reach the surface. I always wake up gasping. I've had a few close calls before (i.e. my reg. freezing and switching to my bailout, or the stupid fucking topside guy not watching the amount of gas left in the botle and running out of air and having to switch to my emergency bailout). It's weird cause I never,ever, think about drowning while working, yet my subconcious must kick it up when I sleep...