Final answer:
The largest body of water in Canada is its lakes, with Lake Superior being the largest one partly situated within Canadian territory. The majority of Earth's freshwater is in icecaps and glaciers, with only a small fraction in lakes.
Step-by-step explanation:
The largest body of water that Canada has most of is its lakes. Canada is renowned for its large number of lakes, with the Great Lakes, which it shares with the United States, being particularly significant. However, when considering the largest singular body of freshwater completely within Canada, Lake Superior is the largest, even though Canada only controls part of it. The second and third-largest lakes entirely in Canada are Great Bear Lake and Great Slave Lake, both situated in the Northwest Territories.
On a global scale, the majority of freshwater is found in icecaps and glaciers, which constitute 68.7% of the Earth's freshwater. Groundwater constitutes 30.1%, while surface water, such as lakes, makes up a mere 0.3%, with 87% of that surface water being in lakes.