The Smoothstone River is a boreal river in northern Saskatchewan that begins at Wabeno Lake in the Waskesiu Upland within Prince Albert National Park, at an elevation of 554 metres, and flows generally northward through boreal forests and muskeg before ending at Pinehouse Lake, a lake along the course of the Churchill River, at an elevation of 384 metres. The total elevation drop across the river's length is approximately 170 metres. The Churchill River system ultimately drains east through Manitoba into Hudson Bay.

The river's course passes through a series of lakes, the largest of which is Smoothstone Lake, situated at the western edge of the Waskesiu Upland. Along the way, the river also flows through Lavallée Lake, which hosts one of the largest concentrations of nesting American white pelicans and double-crested cormorants in Saskatchewan on Heron Island. Emmeline Lake is another named lake along the route. The surrounding landscape is characterized by boreal forest throughout.

A common paddling route begins at Smoothstone Lake and ends at the Besnard Road bridge. The river has been described by those familiar with it as a combination of lakes and Grade 1 rapids, making it a suitable learning river. One paddler noted it was used for high school outdoor education classes out of Big River, suggesting it is accessible to paddlers developing their skills. Early season, higher water conditions have been noted as potentially favorable for the river section accessible via Highway 916.

Access to the river is from Highway 916 and Highway 165. Highway 917 provides access to Smoothstone Lake and its amenities, and Highway 929 dead-ends near Selenite Bay at the lake's northern end. A put-in at Smoothstone Lake has been documented, and the Besnard Road bridge serves as a take-out point for at least one established route. Logging roads may also provide additional access points to avoid paddling the full lake section.