Smoothstone Lake is a lake in the Canadian province of Saskatchewan along the course of the Smoothstone River. The lake is at the western edge of the Waskesiu Upland in the Mid-Boreal Upland ecozone of Canada and is surrounded by boreal forests. Smoothstone Lake's primary inflow and outflow is the Smoothstone River, which begins in the Waskesiu Upland and ends at Pinehouse Lake of the Churchill River. At the lake's northern end is Selenite Point, Selenite Bay, and the 362.2-hectare (895-acre) Shelter Island. Access to the lake and its amenities is from Highway 917. Highway 929 dead ends near Selenite Bay at the lake's northern end.