Hi Greg. Ya, a fire would be really bad. Hell, even a little smoke would be pretty ugly. I really think just a good pair of long johns and hot toddies should be sufficient for the three or four hour dives I expect to make.
Now getting stuck on the bottom for a long time might get cold, but I hope I have enough redundant systems to prevent that. Maybe it's a good idea to wear a wet suit while diving. They keep you warm, and could be useful if an emergency exit was required. I was struggling through a kelp bed on the surface a while back, and even though the water was quite cold, it got REALLY hot in that wet suit. Frank D.