Great posts. One of mine was at 90 feet, night dive, low-vis, I became slightly negative, got a few feet below my buddy and the rest of the group, went to give my BC a bump of air and my light went out. Total darkness with the sound of the turbines at Mansfield dam drumming (seemingly louder and louder). I looked around and everybody was gone. I could not get the light back on immediately, so within a couple of minutes I got my buoyancy stabilized and my secondary light on, banged my tank, still nobody. I had only been diving a short while, and I was pretty freaked out. Of course, when I got to the surface, they were looking for me.