When did ziplines become so prevalent? Somewhere along the way, we went from traveling to places to either relax or explore local cultures to careening through trees on a series of cables. When did this happen? Why are they so popular? Beyond that, I have a hard time believe that everyone staffing these ziplines knows what they are doing. I mean, are there accredited zipline certification programs? If there are, I’m certain that the folks in this video failed to pass the required courses.