The Rivière Vachon flows through the Arctic tundra of Nunavik in northern Quebec, covering approximately 266 kilometres from its source at Lac Laflamme (also known as Manarsulik Lake) at an elevation of 487.5 metres down to its confluence with the Arnaud/Payne River at just 5 metres elevation. The river's Inuktitut name, Ikkatujaaq, translates roughly as "seemingly shallow," though the character of the river belies any suggestion of easy passage.

The Vachon is considered an expedition-level undertaking. Access and paddling difficulties are significant, with long rapids and ledges throughout the descent, compounded by extreme climatic conditions typical of the Nunavik region. The river is only occasionally paddled by canoeists, and it remains one of the more remote and demanding routes in Quebec. Safety protocols specific to the Vachon have been documented through Canadian canoe route resources.

A commonly referenced expedition combines the Vachon with surrounding terrain: an initial roughly 30-kilometre section traversing a chain of small lakes near the Pingualuit crater, followed by approximately 200 kilometres descending the Vachon itself, and concluding with a roughly 70-kilometre crossing of the Kangirsuk fjord to reach the Inuit village of Kangirsuk. The Pingualuit crater, located near the headwaters, is one of the best-preserved meteorite impact craters in the world, nearly perfectly circular at 3.2 kilometres in diameter and estimated at 1.4 million years old.

The river supports a significant Arctic char population, which is harvested for subsistence by the Inuit community of Kangirsuk. The river was named after Bishop Alexander Vachon (1885–1953), rector of Laval University and later Archbishop of Ottawa.