For the diver who wants more light.  With 2,600 lumens and a 6 degree beam angle this will light up the darkest of crevice, even if your eyes are exposed on the daylight coming from above.  

If you're on a night dive and your buddy is getting blinded you can drop it down to 1130 lumens with one press of the switch, and down to 110 lumens with another, which is ideal for not blinding yourself when looking at gauges on a night dive.