Moose Falls, near Yellowstone National Park's southern border, which it shares with Grand Teton National Park, is something of a hidden gem. There is little parking, and the signs for the falls are small. Unlike most easily-accessible waterfalls, it is approached from above, rather than below. It's also possible to approach from either side of the river. Approaching along the southern side of Crawfish Creek allows for, in my opinion, a better view of the falls, such as that shown here.