It is virtually landlocked but is joined to the Arctic Ocean to the north by Foxe Channel and Fury and Hecla Strait, and to the Atlantic Ocean on the east by Hudson Strait. Baffin Island lies athwart the entrance to the bay, and Southampton, Coats and Mansel islands are lodged across the northern gap. The west coast is devoid of islands, but lying off the east is a string known as the Sleepers, Ottawa, Nastapoka and Belcher groups. The maximum length of the bay is 1500 km and its greatest width 830 km.
The bay, including Hudson Strait, is fed by numerous rivers, large and small, including, from west to east, the Kazan, Thelon and Dubawnt, flowing into the bay via Chesterfield Inlet; the Hayes, Nelson and Churchill on the west; the Winisk and Severn in the southwest; the Grande, Eastmain, Nottaway, Moose and Abitibi, Albany, Attawapiskat and Nastapoca, flowing into James Bay; and the Koksoak, flowing into Ungava Bay. The total area of the Hudson Bay drainage is about 3.8 million km2 and the mean discharge of all the rivers flowing into it is 30 900 m3/s.
The bay lies in a huge saucer-shaped basin, fringed by uplands of the Canadian Shield. The basin was inundated by seawater after the retreat of glaciation some 7500 years ago. The bay is generally shallow, and the land is rising steadily at around 60 cm per 100 years because of isostatic uplift, exposing more and more of the coast. The surrounding Hudson Bay Lowland (see Physiographic Regions) is a low plain locked in permafrost and characterized by marshes, peat and innumerable ponds. Much of the hydroelectric potential of the area develops at the point where powerful rivers surge out of the Shield on to the lowlands.
An almost unnatural feature of the east coast is the great, semicircular bight, centering on the Belcher Islands, which it has been suggested was caused by a stupendous meteor strike. The west coast is generally without indentation, low and bleak up to Arviat, and increasingly broken and indented farther north, particularly at the great gashes of Chesterfield Inlet and Rankin Inlet. The shores are mostly covered with brushes, aspen, willow and dwarf birch growing among moss, lichen and grass. Cliffs of ancient sedimentary rocks are found at points on the east coast.
The climate of the region depends largely on the water surface. In January and February the bay is covered with pack ice, preventing any warming effect on the air, and temperatures are consequently very low. The ice begins to melt in May and rapidly disappears in June, when cloudiness and fog increase. The water temperature rises up to 10°C in July and August as a result of the influx of fresh water. During October and November the waters of the bay yield heat and moisture, bringing showers of rain and snow. Fog is most frequent in June, July and August, as warm air cools over the colder water. Winds are strong in all but the summer months and rise to 110 km/h and even 150 km/h in autumn.
Hudson Bay contains great quantities of nutrient salts and small crustaceans occupy the open waters, providing food for molluscs, starfish, sea urchins, worms and other invertebrates. Cod, halibut, salmon and polar plaice are the most common fish. Walrus, dolphins and killer whales live in the northern regions and polar bears migrate south to hunt seals among the ice. Some 200 species of birds including ducks, snow geese, gulls, swans, sandpipers, owls and crows gather on the coasts and islands.
Archaeological evidence has shown that the shores of the bay have been occupied for thousands of years. Many of the excavated campsites are far from the present, receding coastline. At the time of the appearance of Europeans, Algonquian groups inhabited the area around James Bay and Chipewyan groups the Churchill area, and Inuit groups were found on the north and east coasts. Norse seafarers possibly found, and even colonized, the bay, but if so their discovery was forgotten.
Martin Frobisher mistakenly sailed into Hudson Strait in 1578 but Henry Hudson was the first European we know to have braved the dangers of the strait and sailed into the bay (1610). He was followed by Sir Thomas Button (1612), Robert Bylot and Luke Fox [Foxe] (1631), and Thomas James (1631) in a futile search for a passage to the Orient. The voyages were perilous, often disastrous; in 1619 only 3 members of Jens Munk's expedition survived. The mutiny of Hudson's crew passed into exploration mythology. The journals of Luke Fox found their way into Coleridge's harrowing tale, "The Rime of the Ancient Mariner." The west coast was not mapped until the 1820s and the first detailed investigation was carried out from 1929 to 1931.
The bay played a crucial role in the early development of Canada after it was realized that it provided a direct route to the fur resources of the North-West. In 1668 Médard des Groseilliers, in the service of the English, sailed into the bay and built a small post at the mouth of the Rivière de Rupert. In 1670 Pierre-Esprit Radisson founded what later became York Factory at the mouth of the Nelson River, and the trading rights to the entire watershed of the bay were granted to the Hudson's Bay Company (HBC). Posts were later built at the mouths of the Moose and Albany rivers and drew native traders from a vast area of the Shield, with the Cree playing an important middleman role. From 1682 to 1713, the French made a determined effort to rout the English from the bay. Temporary successes were achieved by Pierre de Troyes overland (1686) and Pierre Le Moyne d'Iberville in several expeditions by sea.
Primary Route to the Interior
However, after the Treaty of Utrecht in 1713, the bay was firmly in the hands of the English, and after the HBC merger with the North West Company in 1821, it became the primary route to the interior. On the transfer of Rupert's Land to Canada in 1870, sovereignty over the bay and its watershed also passed to Canada. Since that time it has ceased to play an important role as a transportation route and it has been sparsely populated. The primary occupants continue to be Indian and Inuit bands living by fishing and hunting. The largest settlement is Churchill, Man (pop 1089, 1996c), at the mouth of the Churchill River. Churchill and Mooseonee, Ont are connected by railway to the interior, but their potential as saltwater ports is more often talked about than exploited. The bay remains much as it was; it has been designated for conservation purposes - a mare clausum ("closed sea").