Or, interesting in the opposite direction, I was once on vacation in another country over summer break during elementary school years, visiting a tourist site of some sort, and saw one of my classmates there. Parents didn't coordinate plans or even share them, just a random coincidence that we happened to not only go to the same general area at the same time, not only the same specific tourist location in an area that had a bunch of options, but ended up on the same section of path at the same time.

Makes me wonder how many other times I've randomly been even just an hour away from someone else I knew in an area neither of us were often in.