Hudson Bay, an inland sea of British North America, between lat. 51° and 64° N., and Ion. 77° and 95° W. It is of irregular shape, 850 m. long N. and S., and 600 m. broad. Its S. extremity is called James bay. In its mouth, at the northeast, lies Southampton island; outside of this it communicates with Davis strait by means of Hudson strait, and E. of Southampton island Fox channel extends N. The coasts are generally high, rocky, and rugged. The depth of the middle of the bay has been taken at 150 fathoms, but it is probably more. Southampton island is formed of high rocky masses, and seems to be composed of several small islands separated by straits, always closed however by ice. There are many other islands, and many reefs and sand banks. The principal rivers flowing into the bay are the Great Whale river, on the E. coast; the Main, Abbi-tibbe, Moose, and Albany, into James bay; and the Weenisk, Severn, Hayes, Nelson, Churchill, and Seal, on the W. coast. It was formerly supposed that there were two tides in the bay, one from the east and another from the west; and this error led to the belief in a channel communicating with the western sea, which was thought to be not far distant.

Navigation is possible only during two months, the bay being completely frozen over or obstructed by drift ice during the rest of the year. Before the navigation of the bay was understood, it was usual to take two seasons for a voyage from England; and the captain who succeeded in returning the same year was awarded a prize of £50. Accounts differ as to the abundance of fish in Hudson bay. The Hudson bay company gave little attention to fisheries, yet the white whale is found there, and the whale fishery was once of considerable importance.