I've submerged my Quarq S975 completely- as in, I was riding along a bike path, went into an underpass, and found it was flooded. I stayed up and rode it out (slowly) to the other side, but I was reading my Edge 500 under a couple inches of water. Every sealed bearing on the bike was trashed, but the Quarq was fine and hasn't missed a tick in the 9 months since. Maybe I just got lucky with mine, but my RIKEN hasn't given me any issues either.