I used this product with a head-mounted GoPro camera. Good enough for lighting up any fish a few feet in front of you. I would use this amount of lumens at the very least. More would be better. NOTE: The only way to turn on/off the light is by tightening or loosening the front lens. This won't be easy with wet hands when you are diving, so I suggest using rubber gloves. If you do not fully tighten the unit then the ocean salt water will enter the flashlight and corrode any metal parts and cause the battery to leak acid.