Lavallée Lake sits at the northern boundary of Prince Albert National Park in central Saskatchewan, approximately 59 kilometres north-northeast of Big River, at a surface elevation of 543 metres. The lake is more than 7 miles long and lies within the Waskesiu Upland along the course of the Smoothstone River, which both feeds and drains it, ultimately flowing north into Pinehouse Lake and the Churchill River drainage basin. The lake contains at least one island, Heron Island, and is characterized by high, heavily wooded banks and boulder-strewn shores typical of the lakes in this part of the park.

The lake is designated a Class I Special Protection Zone within Prince Albert National Park, making it an access-controlled area. It is also recognized as an Important Bird Area (IBA SK 004) and hosts the second largest breeding colony of white pelicans in Canada, as well as large numbers of double-crested cormorants nesting on small rocky islands within the lake. This ecological sensitivity directly shapes the regulations governing paddler access and conduct.

Motors are not permitted on the lake, and personal watercraft such as Jet Skis, WaveRunners, and Sea-Doos are prohibited on all park waters. All watercraft must conform to federal small vessel and pleasure craft regulations, and as of April 15, 2025, an Aquatic Invasive Species (AIS) Certification Permit is required before entering park waters.

Lavallée Lake is reachable by canoe from Waskesiu Lake via a chain of lakes including Ajawaan, Lone Island, Little Beaver, and Sanctuary Lakes, connected by portages of varying lengths. From Sanctuary Lake, two portages of approximately 2.5 miles each lead to Lavallée Lake. The route forms part of a longer circuit through the northern section of the park covering nearly one hundred miles and passing through close to a score of lakes. Historical park literature notes that the return from Lavallée Lake to Waskesiu can be made either by the incoming route or by an alternate course.

Fish species present in the lake include walleye, northern pike, lake whitefish, and yellow perch, with specific harvest limits in place under park regulations.