The Niagara Whirlpool is a natural

Natural

Natural is an adjective that refers to Nature.Natural may refer too:In science and mathematics:* Natural transformation, category theory in mathematics* Natural foods...

 whirlpool

Whirlpool

A whirlpool is a swirling body of water usually produced by ocean tides. The vast majority of whirlpools are not very powerful. More powerful ones are more properly termed maelstroms. Vortex is the proper term for any whirlpool that has a downdraft...

 along the Niagara River

Niagara River

The Niagara River flows north from Lake Erie to Lake Ontario. It forms part of the border between the Province of Ontario in Canada and New York State in the United States. There are differing theories as to the origin of the name of the river...

 located along the U.S.-Canadian border between New York

New York

New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

 and Ontario

Ontario

Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

. The whirlpool is located in the Niagara Gorge

Niagara Gorge

Niagara Gorge is a gorge carved by the Niagara River along the US-Canadian border in New York and Ontario. As Niagara Falls recedes upstream toward Lake Erie, the river has gouged the hard dolomitic limestone of the Niagara escarpment to form the gorge...

, downstream from Niagara Falls

Niagara Falls

The Niagara Falls, located on the Niagara River draining Lake Erie into Lake Ontario, is the collective name for the Horseshoe Falls and the adjacent American Falls along with the comparatively small Bridal Veil Falls, which combined form the highest flow rate of any waterfalls in the world and has...

. The whirlpool's greatest depth is 125 feet (38.1 m).

Formation of whirlpool

It is estimated that the whirlpool formed approximately 4,200 years ago by the upstream erosion of the Niagara Escarpment

Niagara Escarpment

The Niagara Escarpment is a long escarpment, or cuesta, in the United States and Canada that runs westward from New York State, through Ontario, Michigan, Wisconsin and Illinois...

 by the Niagara River. Niagara Falls is located along the boundary of the Niagara Escarpment and has been "retreating" upstream since its formation. During this normally slow process, the retreating falls intersected with an ancient pre-glacial river bed inside Saint David's Buried Gorge

Saint David's Buried Gorge

Saint David's Buried Gorge is an ancient pre-glacial river bed that existed 22,800 years ago on the present-day Niagara Peninsula. The ancient Saint David's River once flowed through this area prior to the advance of the Wisconsin Glacier during the last glacial period. When the glacier retreated...

. During the retreat of ice from the Wisconsinan glaciation

Wisconsinan glaciation

The Wisconsin Glacial Episode was the most recent major advance of the North American Laurentide ice sheet. Globally, this advance is known as the last glacial period. The Wisconsin glaciation extended from approximately 110,000 to 10,000 years ago, between the Eemian interglacial and the current...

 of the last glacial period, the gorge was filled with loose sediment and rock. When the falls intersected with this buried gorge, the river quickly washed away the filled-in silt and rocks. The ancient buried gorge was nearly perpendicular to the Niagara River. This sharp and sudden change in direction of water flow, coupled with the rapid flow of water exiting the Niagara Gorge (speeds as high as 30 feet per second [9 m/s]), resulted in turbulent swirling of the river. Further erosion of the harder rock has resulted in a rounded basin that extends just to the side of the actual river's course.

The whirlpool naturally spins in a counterclockwise motion during normal flow. When more water from the river is diverted to the surrounding hydroelectric power plants, however, the flow often reverses.

Nearby attractions

There are two state/provincial parks located alongside the whirlpool. On the U.S. side is the Whirlpool State Park

Whirlpool State Park

Whirlpool State Park is located in Niagara County, New York, north of the city of Niagara Falls. The park overlooks the Niagara Whirlpool on the Niagara River and the lower Niagara Gorge....

. On the Canadian side is the Niagara Glen Nature Reserve

Niagara Glen Nature Reserve

Niagara Glen Nature Reserve is a nature reserve located near the Niagara Whirlpool along the Canadian side of the Niagara Gorge. It is one of the best preserved remaining example of Southern Ontario's original Carolinian forest. The park is operated by the Niagara Parks Commission, an agency of...

. The Whirlpool Aero Car

Whirlpool Aero Car

The Whirlpool Aero Car or Spanish Aero Car is a cable car located in Niagara Falls, Ontario that transports passengers over a section of the Niagara River referred to as the Niagara Whirlpool.-History:...

, which traverses the river above the whirlpool, is also located on the Canadian side.