The Southern Arctic Ecozone, as defined by the Commission for Environmental Cooperation (CEC), is a Canadian terrestrial ecozone which spans the northern coast of mainland Northwest Territories, most of northern mainland Nunavut excepting the northeast peninsula, and a portion of northwestern Quebec. Its two constituent territories are interrupted by Hudson Bay. The ecozone can also be described as including the northernmost part of the Interior Plains of Western Canada and parts of the Canadian Shield located on both sides of northern Hudson Bay.