Yellowstone National Park. October 2004.
Some may find this photo a little hard to look at, but I've always liked it. It can be hard to convey a sense of motion in a still photograph, but this one succeeds in evoking the non-stop rush of water through the rapids, through the shadows of the waves and the distorted reflections of the trees. The vantage point is the high bluff on the northeast side of the river, looking across to the south side where the road and the boardwalk are. Although it's several miles downstream from the outlet of Yellowstone Lake, the river runs so level up to this point that some people think of LeHardy Rapids as the real outlet of the lake.
I'm not sure whether LeHardy Rapids is rising or falling just now. There's a lot of rising and falling going on in Yellowstone, what with a huge magma chamber sitting just below the surface. Through the 1990's, LeHardy was rising at something close to an inch per year, which is pretty damn fast, and was tilting the entire lake up at the north and down at the south. Pretty dramatic stuff, even it was invisible to most of us (visitors to the arms of the lake, however, noticed that some of the campsites were now underwater).