While CarlD is probably correct from a 100% safety viewpoint, I think you are probably 99.999% safe being in the water with one of these cleaners. They are low voltage and are plugged into GFI protected circuits. Your risk of a shock is minute. I think you run a greater risk of a shock from your pool light.

As for the cable strangling you, again these things move very slowly and that is highly unlikely. I think you run a greater chance of getting a toe caught in the unit if you don't watch where it is while you are in the pool.

Bottom line, I would never allow a child in the pool with one of these running, but it is probably fairly safe for an adult swimmer that exhibits just a modicum of common sense and care.

Please don't interpret the above to mean I suggest that you do what is contrary to what the user guide of your equipment states - this is just my opinion based on the way I operate my pool and I take no responsibility legally or otherwise with what you decide to do. (damn I hate lawyers)!!!