The Kuparuk River (Iñupiaq: Kuukpaaġruk) is a river in Alaska's North Slope that enters a bay on the Beaufort Sea between Beechey Point and Prudhoe Bay. The north-flowing river is about 200 mi long, and its delta is about 3 mi wide. Its Eskimo name appeared on a map drawn in 1901 by a prospector who spelled it Koopowra, which he translated as Big River. Kuukpaaġruk can be translated to a "smaller version of a big river". Kuparuk Mound, a 30 ft pingo about 12 mi southeast of Beechey Point, is named after the river. Arctic explorer Ernest de Koven Leffingwell named the mound, which he used as a triangulation station in 1911. The Kuparuk River oil field, the second largest oil field in North America, is centered about 40 mi west of Prudhoe Bay. Discovered in 1969, it covers about 500 mi2.