The Thompson River is the largest tributary of the Fraser River, flowing through the south-central portion of British Columbia, Canada. The Thompson River has two main branches, the South Thompson River and the North Thompson River. The river is home to several varieties of Pacific salmon and trout. The area's geological history was heavily influenced by glaciation, and the several large glacial lakes have filled the river valley over the last 12,000 years. Archaeological evidence shows human habitation in the watershed dating back at least 8,300 years. The Thompson was named by Fraser River explorer, Simon Fraser, in honour of his friend, Columbia Basin explorer David Thompson. Recreational use of the river includes whitewater rafting and angling.

The Fraser River is the longest river within British Columbia, Canada, rising at Fraser Pass near Blackrock Mountain in the Rocky Mountains and flowing for 1,375 kilometres (854 mi), into the Strait of Georgia just south of the City of Vancouver. The river's annual discharge at its mouth is 112 cubic kilometres (27 cu mi) or 3,550 cubic metres per second (125,000 cu ft/s), and each year it discharges about 20 million tons of sediment into the ocean.