Mackenzie River
At , the Mackenzie River drainage basin encompasses nearly 20 percent of Canada. About , or 54 percent of the basin, lies above Great Slave Lake. Permafrost underlies about three-quarters of the watershed, reaching up to deep in the Mackenzie Delta. As a whole, the Mackenzie basin receives only meager to moderate rainfall, averaging over the entire basin, though mountain areas experience much higher precipitation, and areas near and north of the Arctic Circle receive much lower precipitation.
Hudson Bay
Hudson Bay (Inuktitut: "Kangiqsualuk ilua", ) (sometimes called Hudson's Bay, usually historically) is a large body of saltwater in northeastern Canada with a surface area of . It drains a very large area, about , that includes parts of southeastern Nunavut, Saskatchewan, most of Manitoba, Ontario, Quebec and indirectly through smaller passages of water to parts of North Dakota, South Dakota, Minnesota, and Montana. Hudson Bay's southern arm is called James Bay.