The rivière du Pin is a tributary of the south bank of the rivière du Sud (Montmagny) which flows north-east to the south bank of the St. Lawrence, in the administrative region of Chaudière-Appalaches, in Quebec, in Canada.

The Rivière du Pin crosses the regional county municipalities (RCM) of: The Pin river has its source in a mountainous area in the municipality of Saint-Magloire in the Notre Dame Mountains.

From its source, the Pin river "flows in a valley encircled on 30.6 kilometres (19.0 mi) according to the following segments: The Pin river flows on the south shore of the rivière du Sud (Montmagny) at the limit of the municipalities of Armagh and Sainte-Euphémie-sur-Rivière-du-Sud.

The toponym Rivière du Pin was formalized on December 5, 1968, at the Commission de toponymie du Québec.

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