This is an interesting thread-- one of the things I like most about scubaboard is that you get to see how different diving is around the world. So much depends on who and where you are. I've had this lost buddy thing happen to me several times this week actually. It's the first week of ice out here in northern MN, and I've been able to go diving four times with at least one or more buddy, and three of these times we've been separated. All of the dives were in mine quarries, and once you get below a hundred feet the visibility is only a foot or two right now (very dark down there because of layers of suspended silt from meltdown that haven't settled yet). But I have every confidence in myself and my buddies, and if/when we get separated we just continue the dive solo. Doesn't anyone else do that?