I've used my Garrett ATP a lot, for several years, under water for hours at a time. I had zero water problems. And I still like/trust that machine. I have used my Nokta Makro Simplex under water about 4-5 times, for extended periods (hours). And weeks ago I noticed some screen flickering, like an electronic pulse. Then after my last multi hour water session I came out and the screen was pulsing off and on badly, at moderate to high speed. I put the machine into a closet and checked it the next day. The pulsing was low to non existent. I'm dissatisfied with this and I've contacted Nokta Makro. What my experience is telling me is that the situation is deteriorating and should be addressed. Other than that I haven't seen any fuss about the Simplex having water issues. Maybe I got one with a problem. I've used the Simplex non stop all season this year so far, and I like it. No complaints other than this moisture ? related issue............ Any water machine that you are going to submerge should have a little water sprinkled on it a few time to cool the control box down if it sat in a hot car or whatever. A super hot control box going into a much cooler lake can create thermal shock and a vacuum in the housing, just begging to suck water in.