 It begins near Imuruk Lake on the Seward Peninsula and flows generally north to Kugruk Lagoon, at Kotzebue Sound on the Chukchi Sea.The river enters the lagoon southeast of Cape Deceit in the Northwest Arctic Borough.In the late 19th century, the river's Inuit name was reported as "Koogroog" (not to be confused with the Kougarok River), but variants in other documents referred to it as "Mammoth" for mammoth bones found nearby, or "Swan".