The Río Petrohué flows from Lago Todos los Santos westward through Vicente Pérez Rosales National Park in the Los Lagos Region of Chile, draining into the Reloncaví estuary near Ralun. The river is characterized by turquoise water moving through volcanic rock formations, with the snowcapped Volcán Osorno providing a prominent backdrop throughout much of the run. Volcanes Calbuco and Puntiagudo are also visible from the river corridor.

The most notable feature along the river is the Saltos de Petrohué, a series of waterfalls where the water charges through channels carved into old lava flows. Rafting and kayaking take place below these falls, on a section rated Class III. Commercial operators describe the run as approximately one hour on the water, combining fast-moving rapids with calmer stretches. The river is also used for full-day kayak descents that continue to the river's mouth at the Reloncaví estuary, with a lunch break mid-route. The estuary section near Ralun is used for flatwater kayaking, with at least one operator offering access to a private put-in at the tidal mouth.

The best conditions for whitewater paddling are generally from December through March, when flows are at their peak due to the combination of rainfall and seasonal glacial meltwater. Multiple commercial operators run trips from Puerto Varas and from Ensenada, with transport to the put-in typically included. The Petrohue Lodge, situated on the shore of Lago Todos los Santos at the river's headwaters, serves as a base for organizing river activities.

The river runs entirely within Vicente Pérez Rosales National Park, Chile's oldest national park, established in 1926, so paddlers should be aware of any park regulations that may apply. The river is well regarded for fly fishing, with trout present throughout. The overall character of the paddling experience combines accessible whitewater in a volcanically shaped landscape, with the river's distinctive turquoise color a consistent feature noted across the full length of the run.