In looking through the pics of the divers working on Costa Concordia I saw what looked like a UW Kinetics Q40 attached to one of the dive helmets. 2-watt LED running 4 AA lithium batteries and waterproof to 500 ft. That should be deep enough on a cruise ship. wink

I've got an older (less lumen/more run-time) version of the UK4AA eLED as one of the lights in my aviation survival vest. Not a dive light, but I don't expect to be very deep. (if I get deeper than 10 ft I have bigger problems than a light not working)
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Better is the Enemy of Good Enough.
Okay, what’s your point??