On the outskirts of Niagra Falls, they have the “White Water Walk”.  It is a boardwalk that goes along the Niagra River, and gives you a view of the Class 4/5 rapids.  It isn’t thrilling, but it was a very nice break from getting wet all the time.  It also gave me some time to actually think about taking pictures, and even to use my neutral density filters.  You can tell when it is being used as the water looks silky.