3-in-1 falls
Despite its name, Niagara Falls actually consists of three different waterfalls: American Falls and Bridal Falls located on the New York side, and Horseshoe Falls found on Ontario’s side. Horseshoe Falls is arguably the most beautiful waterfall of the three due to its unique horseshoe-like shape.
If you blocked the flow of water to any one of these falls, the water would attempt to gush through the remaining two. This is what engineers were relying on when they blocked off the American Falls out of fear that it was causing erosion at an alarming rate.