Canada has five main ocean watersheds, also called drainage basins: the Atlantic (which includes the Great Lakes and the St. Lawrence River), the Arctic, the Gulf of Mexico, Hudson Bay and the Pacific. Each of these enormous areas is comprised of a network of smaller watersheds, most of which are connected by configurations of streams and rivers, called tributaries, that route water to an ocean.
This map shows Canada's five ocean drainage basins. Areas of higher elevation are shaded lighter than low-lying regions. When you roll over an ocean watershed, directional arrows will appear to show where the water flows. Their thickness is proportional to the area drained; the wider the flow line, the larger the area drained.
