Another usual sign of shark agression is holding the pectoral fins at a sharp 45 degree downward angle instead of relatively flat. It indicates a relatively "pissy" mood (as well as the arched back).
I dove in the Exumas with Caribbean reef sharks for my first shark dives - not on a feed, just regular dives and there were about 3 or 4 milling around the sites. I was a bit nervous my first time, but I soon saw that there were also about a zillion jacks hanging around as well. I figured from the shark's point of view, there were a zillion hamburger-sized fish and a couple cow-size divers. Hmmm....if *I* were a shark, which one was I going to go for? A bite-sized hamburger or a great big cow-sized diver blowing bubbles and easily as big as me and likely to fight back?
That settled me down a lot.
That's not to say that I didn't have a little adrenaline rush when one decided that noise from the autofocus in my camera was interesting and ran at me head-on, only to turn away about 3 feet from me. I just held up my housing, ready to ram it in the nose and give him a good mouthful of polycarbonate if he wanted a bite. When he turned aside, I at least had the presence of mind to get a good picture.
Took my heart a couple of minutes to slow down after that one....
I've dived with sharks a number of times since then and been fine. I just keep my distance, keep my cool and keep an eye on them. I don't chase them, I respect them and I'm always grateful when I get to dive with them.
