The Radium King was built in 1937 to haul ore on the Mackenzie River, and her tributaries. This included uranium used in the US atom bombs of World War II. Later in her active career she hauled barges on Great Slave Lake.

The Radium Queen and her sister ship the Radium King were built in Sorel, Quebec in 1937, for the Northern Transportation Company, a subsidiary of Eldorado Gold Mines. The Radium Queen was a cargo/tug ship that served on the Slave River. It made runs between Lake Athabaska and Great Slave Lake which is generally navigable. The Radium Queen towed barges from the railhead at Waterways, Alberta to a portage around the rapids. Cargo was unloaded there and transported by land, and loaded on barges on the lower river that were towed by the Radium King, and later by other tugboats, like the Radium Charles, Radium Express and Radium Yellowknife.