One piece of advice for the Emerald - maintain an awareness of where the sharks are. One, I've had a number of dives where I've seen something cool (like a scalloped hammerhead on the deep ledge or a tiger on a lobster dive) that I've caught for a blink or two before they vanished. Two, you really want to know where all the sharks are, especially the tigers. If one shows up the lemons are much less of a concern. The last time I was out one guy turned his back on a juvenile tiger and she started sniffing the back of his tank. Would she have done anything? I don't know, but Randy hit the buzzer and and I swam over to push her off. Guy had no idea there was a 7-foot shark back there until the end of the dive when I asked him how big of a brick he dropped in his wetsuit.
It's an awesome dive; however your situational awareness has to be higher than normal. Listen to the instructions from Randy and follow them - no waving hands around, no getting in the chum line. A wetsuit is probably a good idea; I break out my hood even at this time of year to minimize the amount of skin showing (especially the nice patch right at the back of my head that's cropped up). On the second and third dives you'll be sitting on the deck of the Esso Bonaire for the start of it, which has all the requisite scraping and stinging hazards of rusty, encrusted metal.