Niagara Falls is the second largest falls on the globe next to Victoria Falls in southern Africa. One fifth of all the fresh water in the world lies in the four Upper Great Lakes: Michigan, Huron, Superior and Erie. The entire outflow empties into the Niagara river and eventually cascades over the falls. At the bottom of the falls, the water travels 24 kilometres (15 miles) over many gorges until it reaches the fifth Great Lake: Lake Ontario. The Canadian Horseshoe Falls drops an average of 57 metres (188 feet) into the Lower Niagara River. More than 168,000 cubic metres (6 million cubic feet) of water go over the crest line every minute during peak daytime tourist hours. The crest line of the Canadian Horseshoe Falls is approximately 670 metres (2,200 feet) wide.