I can remember the exact moment when we saw this rainbow at Iguazu falls. We were on the Brazil side of the falls (our first day) and were walking out on a long boardwalk-like walkway which takes you over the river and right in front of a big portion of the falls. We spotted the rainbow and I quickly snapped off the photo.
As you can probably also see, there was a ton of mist from the falls which meant that everyone was getting soaked. It was the type of mist that makes you think it’s not that bad and then 30 seconds later you realize you’re completely drenched. But, with temperatures around 100 F, the water was refreshing and quite welcome!