I know it's impossible to have clear vision when not wearing a mask underwater. I had always assumed everybody saw the same I see: nothing at all. But during one of my dives I saw someone lose his mask, and go to the bottom and find it without any trouble (I don't think he could see it falling so as not to lose track of it, since it caught him unawares when someone else kicked it off). If someone's in front of me, at a distance of, say, four feet, I can see a dark blur, but I would never be able to tell whether it's my instructor or a seal, and I think I wouldn't be able to recognise anyone even if he were very close to me, let alone see my mask on the bottom if I lost it. What is the normal thing, being or not being able to do it?