Trois-Pistoles is a city in Les Basques Regional County Municipality in the Bas-Saint-Laurent region of Quebec, Canada. It is also the county seat. The town is located on the south shore of the Saint Lawrence River. A ferry crosses the river to Les Escoumins on the north shore. The port facilities are also used by fishing boats and scuba divers. The town is the site of the University of Western Ontario's annual French immersion program, which has existed since 1932.