Wide Angle Underwater

I've tried a bit of close-focus wide angle, but the best I can do with the 16-35 isn't very impressive.  I worry a lot about scratching the dome port as I've banged it into more than one subject when I didn't think I was that close.

Mostly I'm not that good at wide angle, but just in this thread I've learned something - my 16mm shots turn out to be more interesting than my 35mm.   Then too, an awful lot of my 35mm shots are frustrated 50 and 60mm shots.  I'm going to explore the wide end more, and basically start by having at least one element close to the camera.

White balance is an issue if I try to use my strobes.  This last trip in Roatan I got much more practice shooting wide angle because I lost one of the strobes in the first few days of the trip.   I had already shot everything in sight with the 105mm for a few days, plus the previous trips, so I resolved to stick with the 16-35 for several days, regardless of conditions.  Since I was down a strobe anyway, it was more pressure to shoot ambient with wide angle.

Once I went to ambient, my ISO settings quickly became an issue - how high is too high? For the way I shoot and post-process, going up to 800 is a real struggle.  I lose so much dynamic range that I can't make the shot come out the way I want.   I then practiced setting lower limits, but if my upper limit is only 200, I underexpose too much.   Going below 1/160th is generally going to give me blurry fish and some corals, so I sometimes just plain run out of effective lighting.