The Río Cholguán is a free-flowing winter and spring run in Chile's 8th Region, draining the peaks of Cordón Infiernillo (1,972 m), Blanquillo (1,780 m), and Cordón Cholguán (2,148 m). It forms the border between Provincia Biobío and Ñuble. The name derives from a Mapuche word meaning "clam." In early season the river is fed by snowmelt, transitioning to rain-fed flows later in the season.

The run is continuous Class 3 with wave trains throughout. The described route begins on the small tributary Río Congrejo, where flows start around 100 CFS. After joining a branch of the Cholguán, flows increase to approximately 350 CFS, and within another 1–2 km additional branches converge to bring the total to around 700 CFS for the remainder of the trip. The total run length is 13.4 km to the takeout at the confluence of the Río Cholguán and Río Congrejo.

To reach the put-in from Ruta 5 in Los Angeles, take the road toward Antuco (Río Laja) for 30 km, then head north 43 km to the town of Yungay. From Yungay, travel east on paved road (Calle Angamos) for 12.5 km, where the road turns to gravel. At km 21.3, turn right toward Santa Lucía and follow the road down to the valley floor. The put-in is at a small bridge over the tributary Río Congrejo. A riverside camp is available approximately 2.2 km above the takeout.

One notable consideration for trip planning is a hydroelectric diversion project called Proyecto El Pinar, which was under construction just upstream of the put-in at the time of the report. It was unclear whether this project would affect future boating conditions, so paddlers should verify the current status of this project before planning a trip.