Yellowstone National Park. Unfortunately, our photos got lost and deleted somewhere between camera and computer, but thankfully, one of our other cameras got a few photos in too.
We were lucky enough to see Old Faithful blow two times. The wee ones were on a quest to become Junior Rangers and get a badge. The funny thing is after they took the junior ranger pledge and were 'sworn in', they got the badge and were more impressed with the safety pin being GOLDEN. They had never seen a gold colored safety pin. They thought that was the coolest!