Started out in Bozeman, stayed a first night in Mammoth Hot Springs, stayed several days around Old Faithful, and then back to the Mammoth Hot Springs area for the Wolf Discovery tour.
These appear to have occurred naturally all over the place in one area. The guide had never seen them before either. - February 02, 2011 - 1/6400 sec at f / 13 - 52 mm - ISO 200 - 44°36'2" N 110°50'3" W