The geography of Manitoba addresses the easternmost of the three prairie Canadian provinces, located in the longitudinal centre of Canada. Manitoba borders on Saskatchewan to the west, Ontario to the east, Nunavut to the north, and the American states of North Dakota and Minnesota to the south. Although the border with Saskatchewan appears straight on large-scale maps, it actually has many right-angle corners that give the appearance of a slanted line. In elevation, Manitoba ranges from sea level on Hudson Bay to 2727 ft (831 m) on top of Baldy Mountain. The northern sixty percent of the province is on the Canadian Shield. The northernmost regions of Manitoba lie permafrost (permanently frozen subsoil), and a section of tundra bordering Hudson Bay.