Seeing as you're from Ohio and diving in a quarry with limited visibility, unless you're planning on traveling somewhere where the water is much clearer and full of little things to shoot (unless you like shooting macros of zebra mussels and rocks), you may find that shooting at night is going to require some investment in external lighting.
I do a lot of wide angle wreck photography, and while I generally prefer to shoot during the day, at times, there can be little ambient light which, for all intents and purposes, makes it really a night-like dive. The issues at night, for me, is having sufficient light for the camera to focus properly, as well as having sufficient lighting to illuminate your subject area.
The issue I find with shooting wide angle and using the modeling lights on your strobe is that the strobes are generally not pointed at where the camera needs the light to focus. I've attached a focus light to my setup to assist specifically for focusing, but the issue with this is that the light is really not strong enough to assist for the wide out shots (eg. shooting the stern of a wreck, for example). If it *is* strong enough, then you end up with a star wars like beam in your shot (interesting in a few shots for the effect, but really, I wouldn't want all my shots like that). An actual focus light synced with your camera to shut off while it fires the shutter may be the answer, but in general they are pretty expensive and in the end, I don't know if they'd be powerful enough to serve my purpose.
So what would I suggest? Well, having external strobes is pretty well a given unless you're shooting up close or macro. As well, a focusing light will help as well, but if you're any distance more than a few feet out, it may not work so well. What I do often on night-like dives is to use my HID in my left hand to point to the focus area, lock focus with my camera, move the HID away (while holding the frame, shutter button pressed half way - not too hard to fire, and not too light to lose the lock) and then fire. It's a lot to do all at once, but it seems to work reasonably well. Sometimes I fire without moving the HID beam - that will happen once in a while.
Here are a few shots I took of a wreck called the Boland in Lake Erie last week on a night dive. I used the HID to assist focus. As you can see in the stern shot, I left the beam in. The others, I moved them.
My buddy Rob heading along the wreck.
My other buddy Kevin following up with me at the rear.
The overturned stern.
Inside a cargo hold
