The Assiniboine River is a 1,070-kilometre (660 mi) river that runs through the prairies of Western Canada in Saskatchewan and Manitoba. It is a tributary of the Red River. The Assiniboine is a typical meandering river with a single main channel embanked within a flat, shallow valley in some places and a steep valley in others. Its main tributaries are the Qu'Appelle, Souris, and Whitesand Rivers. For early history and exploration see Assiniboine River fur trade.

Saskatchewan is a province in Western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the United States. Saskatchewan and Alberta are the only landlocked provinces of Canada. In 2023, Saskatchewan's population was estimated at 1,225,493. Nearly 10% of Saskatchewan's total area of 651,900 km2 (251,700 sq mi) is fresh water, mostly rivers, reservoirs, and lakes.