The gulf will have larger, stronger fish to shoot. Be prepared for possible entanglements, and free rides through the water from some of the fish you may shoot (larger amberjack, cobia, etc). Target depths are usually 60-110ft, so you will be narced. Pay very close attention to nitrogen loads, gas supply, and o2 toxicity if you're diving Nitrox. SOME divers
find that sharks like to challenge them for their catch. It's not yet happened to me, but it's a real possibility. Read through some spearfishing threads here and in the
UNDERWATER HUNTING section to get an idea of what other challenges you may face.
As for diving in the Gulf, conditions have been very good recently, and hopefully they will hold out.
Listen to the Captain's/Dive Master's instructions What they are going to tell you is
IMPORTANT Specifically, upon making entry,
get to the safety line. Don't let go of the safety line until you are sure you are out of the surface current. I have seen many, many divers burn 1/3 of their tank because they let go of the line, and then had to swim against a surface current for a minute or two to get back on the line, or, they refuse to go hand-over-hand to the anchor line, and they burn even more gas. Just don't let go. Make sure you have a whistle and a surface marker buoy (the taller the better) in case you find yourself surfacing away from the boat.