Great shots! I like the softer foreground light in your "failed" strobe image Chip. I note you've also got some of those nice DIR divers who swim around with their non-torch hand out in front as well - it's a good place to put your strobe sensor.
I agree with Lee on the safety front, I usually only take photos on the journey into the cave and I avoid taking them immediately after turning for home. Photos inbound also takes advantage of the clear water. Even if it's not silty on the way out it will be slightly milky from bubbles through the water.
If people are coming this way with cave diving photography in mind, get in touch! We have some speccy caverns close to civilisation and some even better large caves out in the back of beyond. A few more decorated caves would make me very happy but you can't have everything.