Hudson Bay drainage basin
The Hudson Bay drainage basin is the drainage basin in northern North America where surface water empties into the Hudson Bay and adjoining waters. Spanning an area of about 3,861,400 square kilometres (1,490,900 sq mi) and with a mean discharge of about 30,900 m3/s (1,090,000 cu ft/s), the basin is almost entirely within Canada.
Source: Wikipedia — Hudson Bay drainage basin (CC BY-SA 4.0)