teknitroxdiver:I disagree with the third item. Think about it: A shark emits no bubbles (normally, at least), so if the theory of 'no bubbles=tame fishies', do you really think the fishies would still be there to look at? Fish don't survive by being friendly with a 6' long neoprene-covered object that's trying to get closer to them....
Sharks move quickly and their presence ,when displaying predatory behavior, creates a reaction that is observable in other marine life that is a trigger to marine life that are not even aware of the shark. On a rebreather with no bubbles, moving slowly and silently you can get very, very close to marine life. An unspoken danger of rebreather diving is that you may bump your head on a fish-soo watch out!