Moving water photographed with a neutral density filter can blur water, turning it into a smooth, white stream. The reflective surface of calm water is also an attractive target for the camera lens.
Nighttime photo of Niagara Falls. Niagara Falls, NY.
Rapids, downstream from the falls. Niagara, Canadian side.
Bailey Fountain at the Grand Army Plaza. Brooklyn.
Reflection of fallen branches on the quiet water. Prospect Park, Brooklyn.
Yes, that is a person to to the left of the waterfall, climbing up the trail as it goes behind the waterfall. Iceland.