OK... there may be millions of visitors that take the "Maid of the Mist" tour, but probably 90% won't have a photo with this perspective...
BUT.. ;O) you can do MUCH better with the tags.... before I forget.. add you name as a tag to all your images. Also along with niagra falls as a tag, include separatly niagra, and falls. each are unique. Don't forget colors.... decorators search for spcefic colors.. so add blue, blue green, green. Now lets add some more obvious ones.... nature, outdoors, vacation, honeymoon, marriage, wedding, turbulent, wild, misty (different than mist), spray, tour, boat, ship, exciting
well I think you get the idea... there are more to add...
Some people also like to tell stories in their descriptions to get google to find the image as well. It might even get a customer to decide to purchase if it happens to be something they can relate to.
bob