Canada has the largest inland water area in Wikipedia's total-area table. The table lists about 891,163 square kilometers of inland water for Canada, ahead of Russia at roughly 721,380 square kilometers and the United States at about 377,424 square kilometers.
That huge figure reflects Canada's exceptional number of lakes, rivers, and reservoirs. Glacial erosion during the last Ice Age carved and deepened countless basins across the Canadian Shield, leaving a landscape dotted with freshwater. The country contains portions of four of the five Great Lakes, as well as enormous lakes such as Great Bear Lake and Great Slave Lake.
A common mix-up is confusing inland water with total water area or maritime territory. Wikipedia's inland-water column counts internal lakes, reservoirs, and rivers; it does not count territorial seas or exclusive economic zones. Canada is also often called the world's second-largest country by total area, behind Russia, but it leads this particular water-area comparison.