
The Niagara Falls are voluminous waterfalls on the Niagara River, straddling the international border between the Canadian province of Ontario and the U.S. state of New York. The falls are 17 miles north-northwest of Buffalo, New York and 75 miles south-southeast of Toronto, Ontario, between the twin cities of Niagara Falls, Ontario, and Niagara Falls, New York.
Niagara Falls is composed of two major sections separated by Goat Island: Horseshoe Falls, the majority of which lies on the Canadian side of the border, and American Falls on the American side. The smaller Bridal Veil Falls are also located on the American side, separated from the main falls by Luna Island.

The Niagara Falls are renowned both for their beauty and as a valuable source of hydroelectric power. Managing the balance between recreational, commercial, and industrial uses has been a challenge for the stewards of the falls since the 1800s.
The volume of water approaching the falls during peak flow season may sometimes be as much as 202,000 cubic feet per second . Since the flow is a direct function of the Lake Erie water elevation, it typically peaks in late spring or early summer.
This is accomplished by employing a weir with movable gates upstream from the Horseshoe Falls. The Falls flow is further halved at night, and during the low tourist season in the winter, remains a flat 50,000 cubic feet per second.

Water diversion is regulated by the 1950 Niagara Treaty and is administered by the International Niagara Board of Control Viewpoints on the American shore generally are astride or behind the falls. The falls face directly toward the Canadian shore. Thus, the most complete views of Niagara Falls are available from the Canadian side of the river.