Just to comment further on this well discussed topic; putting the mask up on the forehead is not something that is taught as a signal of distress or trauma. It is something that distressed divers do almost upon instinct after they spit their regs once they make it to the surface. This is why it is best not to wear the mask this way as a choice, its better to wear the mask some other way. From a distance, it is hard to tell whether a diver is in trouble or just relaxing and a boat crew will usually always assume there is trauma if they see a diver with his/her mask up { esp. if there is any kind of chop out there }. Again, I am not trying to flame anyone.