T-thumbs,
You are exactly right... they are totally quiet as they swim by AND no matter what size they are, they look like they are 8-feet long when you are in the water with them until they go over you! Our shark dive off of Paradisio Reef in 1987 brought on some 4-footers that were a little too friendly, and 6-footers that looked very hungry. They were rubbing against us (12-divers) and gave us quite a show. I have never been so glad to get back into a boat... but the adrenaline rush was like no other.