The fresh water that plunges over Niagara drains approximately 684,000 square kilometres (261,000 square feet) of water from four great lakes-lakes Superior, Michigan Huron and Erie. Once it flows over the falls it travels the Niagara River 21.7 kilometres (13 ½ miles) to Lake Ontario. From there, it travels down the St. Lawrence River to the Atlantic Ocean.

One-fifth of the world’s fresh water is found in these four great lakes.