Lower Falls of the Yellowstone River, and Rainbow. I had read that a rainbow sometimes forms at the lower falls of the Yellowstone River in the Grand Canyon of Yellowstone. So, I got up early, and made the approx. 1/2 mile hike and 300' down to this viewpoint of the falls. I had been there over an hour, and about to give up that a rainbow would ever appear. Then the first and only people to join me at the viewpoint arrived. The gentleman was shorter, with a 4" white beard on his chin only. His wife was equally pleasant and diminutive. I chatted with them for a few minutes (telling them I was hoping for a rainbow), while they snapped a few shots with their point and shoot. As they left, the gentleman told me that he thought the rainbow would appear soon. The wife then whispered to me with a smile that every St. Patrick's Day her husband dressed up as a Leprechaun. Within 2 minutes of them leaving the rainbow started to appear!! True Story!