The class 4, class 4+ Río Ralco flows through an enchanting, basalt canyon drenched in luscious springs, and draped with water-loving chilcos (Fuchsia magellanica), a fuchsia-like flower with bright red sepals and bluish-purple petals. Its sparkling water courses through a maze of boat-scoutable, pool-drop rapids. None of the drops are very tough, but be wary of submerged logs
Ethan Greene in the Araucaria forest put in for Rio Ralco 1998
To reach the take out exit ruta 5 at Los Angeles (or Mulchen if traveling north) and take paved road 42 km to Santa Barbara then continue on another 52 km to town of Ralco. Soon after the town of Ralco the road will turn to stone but continue onwards up the Bio Bio valley towards Reserva Nacional Ralco for approximately 45 additional kilometers (unfortunately en route you will pass both dam sites.) At town of Lepoy follow a dirt road down to a bridge over the river at elevation 670 meters.
To reach put-in return to Lepoy and continue up a steep road approximately 8 KM to Fundo El Barco elevation 970 meters. Ask permission to enter for easy access to the river and/or for permission to camp. Araucaria trees majestically line the shore at the put-in, while Volcán Lonquimay (2890 m) simmers ominously in the distance. Request permission to camp in this lovely place.
Once on the river you will enter a canyon which contains fun pool drop rapids and the crux of the whitewater. After 5.5 km you will reach the confluence with the Rio Lomin and flows will double. After 2 more km the Chaquilvin river enters from the left and soon after you will reach the takeout.
Due to small size the run is best in spring or early summer flows with ideal volume 250 to 400 CFS.