okay, confession time. I dropped my light on entry of a night dive. I'm the instructor, doing the night portion of adventure diver cert. And I dropped it at the bouy line... The light was ON though. I looked at the group, they looked back..... My light was at the bottom about 13 meters down.
I said, " Now, I want you all to see this. This is how the beacon I'm about to hang on the descent line will look from a distance. I dropped this light because I want you to see how will look down there so you can recognize it...... " One little voice at the end said," Yeah, right." I laughed and made my DM babysit while I went and got my light, and hung the beacon. Back at the top, I explained that this would happen to any idiot who forgot to tether the lanyard to them..... I haven't forgotten in a long time.