I'll grant the freshwater bit pushes the probability down a fair bit. But the comment that I was responding to was "Doing that sort of travel is, for most citi

I'll grant the freshwater bit pushes the probability down a fair bit. But the comment that I was responding to was "Doing that sort of travel is, for most citizens of the industrialized west, pretty unusual." which seems to be more about "outside of Europe" than it was "and swimming in freshwater. That was the part I found strange. I think there's a couple of countries with much lower than average travel (the US already mentioned and I seem to recall that the French tend to stay within their own borders more than the average)