A river is a course of water, usually growing in volume between its source and its terminus in an ocean, a lake or another river. A stream or riverlet is smaller but the volumes involved are not closely defined. Longest Rivers In Canada:-
1. Mackenzie:- At 2,635 miles (4,240 kilometers) long, the Mackenzie River is the longest river in Canada, the second longest river system in all of North America, and the twelfth longest in the entire world.
2. Yukon:- At 1,979 miles (3,184 kilometers), the Yukon is the second longest river in Canada.
3. Saint Lawrence:- At 1,900 miles (3,057 kilometers), the Saint Lawrence is the third longest river in Canada.
4. Nelson:- At 1,600 miles (2,574 kilometers), the Nelson is the fourth longest river in Canada.
Source:-
1. http://www.thecanadianencyclopedia.ca/en/article/river/
2. https://www.worldatlas.com/articles/the-longest-rivers-in-canada.html