Niagara Falls is an amazing place. It is not the height that is impressive, but the shear size and the volume of water that goes over it. Approximately 150,000 US gallons or 567,800 liters go over the falls every second! The Maid of the Mist boat in the thick of it gives some good contrast.
American Photo Blog 
We live 15 minutes from the Falls and its wonder never ceases to amaze me even after all these years!!
I agree. I have been going to Niagara Falls for almost 20 years, and its shear power is simply awesome!
Amazing wonder of Nature.