Horseshoe Falls, Niagara Falls, ON. I took this while hanging onto a big rock behind a restaurant at the edge of the falls. In post processing I just cropped a bit and increased the contrast. I also tried leveling the horizon but found it looked less dramatic.

Olympus E-620 with Zuiko 14-42mm zoom @ 16mm
F/7.1, 1/250 s, ISO 200