That was an interesting trip. I went caving with nine others. The basic plan was to enter the cave by a 40-foot pit, then do an instrument survey of the cave in order to produce a cave map. While I was in the bottom of the pit waiting for the next person to rappel down the rope, I looked around for wildlife. One lonely millipede was hanging on the ceiling looking for a meal. The others tossed my cave pack down the rope, and it hit a ledge and then hit me in the helmet. That’s why helmets are mandatory. An hour or two later, I returned to my pack to fish out some extra lighting for photography. This was a 10,000 lumen LED continuous light. Apparently in the fall and the ledge hit, the on/off switch was hit, so the darn thing had been burning on maximum intensity for that time. It was very hot, and it had already used up over half of the battery charge. I’ll never need to worry about hypothermia in a cave as long as I have that bright light.