If anyone is going to use this in a swimming pool when they get it, make sure you wear your glasses without exception. When taking this profile pic, the water was way choppy, and the beam was dancing all over the place; it'll b the same under the surface. If you have a round swimming pool, it will reflect into your eyes. I would also like to see how quickly one of these can burn into a pool lining, because the effect of convection of the water should help reduce local heat, but the radiation is very localized. Anyone willing to sacrifice their pool? For science.
I'm not planning in the anywhere future for a under water laser but I hate to admit I probably wouldn't of thought of number of possible reflections