The Rivière du Gouffre Sud-Ouest (English: South-West Pit Cave River) is a tributary of the eastern bank of the intermediate part of the Rivière du Gouffre, flowing in the unorganized territory of Lac-Pikauba and the municipality of Saint-Urbain, in the Charlevoix Regional County Municipality, in the administrative region of the Capitale-Nationale, in the province of Quebec, in Canada.

The water level of the river varies with the seasons and the precipitation; the spring flood generally occurs in April.

The Gouffre Sud-Ouest river takes its source from Prime lake (length: 1.6 kilometres (0.99 mi); altitude: 724 metres (2,375 ft)) located in forest area and encased in the mountains.

The mouth of this lake is located at the bottom of the bay southeast of the lake, either: From Prime Lake, the course of the Gouffre Sud-Ouest river descends on 29.5 kilometres (18.3 mi) in a generally deep valley, with a drop of 518 metres (1,699 ft), depending on the segments following: The Rivière du Gouffre Sud-Ouest flows downstream from a river loop on the west bank of the Rivière du Gouffre, in the municipality of Saint-Urbain.

[1] According to research carried out in cartography, this toponymic designation appears on the regional map of the Ministry of Lands and Forests, 1915 edition.