List of longest rivers of Canada
Nine rivers in this list cross international boundaries or form them. Four—the Yukon, Columbia, Porcupine, and Kootenay—begin in Canada and flow into the United States. Five—the Milk, Pend d'Oreille, Saint Lawrence, Red, and Saint John—begin in the United States and flow into Canada. Of these, the Milk and the Kootenay cross the international border twice, the Milk leaving and then re-entering the United States, the Kootenay leaving and then re-entering Canada. The drainage basins of these nine rivers extend into both countries; in addition, the drainage basins of six others—the Fraser, Assiniboine, South Saskatchewan, Saskatchewan, Nelson, and Winnipeg—extend into the United States even though their main stems flow entirely within Canada.
Geography of Canada
Canada holds vast reserves of water: its rivers discharge nearly 9% of the world's renewable water supply, it contains a quarter of the world's wetlands, and it has the third largest amount of glaciers (after Antarctica and Greenland). Because of extensive glaciation, Canada hosts more than two million lakes: of those that are entirely within Canada, more than 31,000 are between in area, while 563 are larger than .