Samm Sheperd of YouTube decided to build a water-cooled LED flashlight with a LOT of light power. Specifically, he built one with 72,000 lumens.
In this video, he demonstrates exactly how powerful it is...
The video started automatically at 1:58, when they start testing the giant flashlight in comparison with other "good" flashlights. However, if you're curious about how he designed the giant flashlight and put it together, you can watch the video from the beginning.
Some questions and answers from the YouTube description:
Q: why are you only turning it on for short bursts?
A: The reason is just that I only had one night with the camera guy to get all the shots and I was paranoid of losing battery. The other reason is that it's so bright that it's annoying and I loose the ability to see at night
Q: Will it eventually overheat?
A: No, it can run off a power supply continuously with a stable coolant temperature.
Q: How long does the battery last?
A: The small battery back I'm using is made out of batteries I already had, and they will last 6 minutes. A bigger battery is easy
Q: Can I buy one? How much?
A: I am only considering because so many people ask, but it would be like $700 and take a month and a half to order parts and make it and ship it. For serious inquiries, firstname.lastname@example.org