Hudson Bay, sometimes called Hudson's Bay, is a large body of saltwater in northeastern Canada with a surface area of 1,230,000 km2 (470,000 sq mi). It is located north of Ontario, west of Quebec, northeast of Manitoba, and southeast of Nunavut, but politically entirely part of Nunavut. It is an inland marginal sea of the Arctic Ocean. The Hudson Strait provides a connection between the Labrador Sea and the Atlantic Ocean in the northeast, while the Foxe Channel connects the Hudson Bay with the Arctic Ocean in the north. It drains a very large area, about 3,861,400 km2 (1,490,900 sq mi), that includes parts of southeastern Nunavut, Alberta, Saskatchewan, Ontario, Quebec, all of Manitoba, and parts of the U.S. states of North Dakota, South Dakota, Minnesota, and Montana. Hudson Bay's southern arm is called James Bay.

Ontario is the southernmost province of Canada. Located in Central Canada, Ontario is the country's most populous province. As of the 2021 Canadian census, it is home to 38.5 percent of the country's population, and is the second-largest province by total area. Ontario is Canada's fourth-largest jurisdiction in total area of all the Canadian provinces and territories. It is home to the nation's capital, Ottawa, and its most populous city, Toronto, which is Ontario's provincial capital.