Nangmagvik Lake sits within Aulavik National Park on Banks Island in the northern Northwest Territories, at coordinates 74°09′02″N 120°00′11″W. The lake lies just 1 metre above sea level and covers approximately 3.61 square kilometres, stretching roughly 4.4 kilometres in the north–south direction and 1.4 kilometres east–west, giving it an elongated shape. The surrounding terrain is barren arctic tundra with little or no vegetation, and the area is essentially unpopulated, with fewer than two inhabitants per square kilometre.

The lake is notable for supporting landlocked Arctic char, which are found in several of the larger lakes within Aulavik National Park, Nangmagvik among them. Wildlife in the broader park includes muskoxen, migratory birds such as brant and snow geese, and sandhill cranes, reflecting the ecological richness of this high-arctic environment despite its sparse vegetation.

A cabin at Nangmagvik Lake, commonly referred to as the Polar Bear cabin, was constructed in 1987 by the Government of the Northwest Territories and originally served as a base camp for wildlife research. This represents the only permanent structure in the immediate vicinity and may be relevant to paddlers planning extended stays in the area.

Aulavik National Park as a whole sees extremely low visitation, with annual backcountry use typically reaching no more than twenty visitors. The park is primarily accessed by air, with designated air access points identified in park management plans. The Thomsen River, which flows through the park, is the primary paddling destination in the region, and Nangmagvik Lake is situated within this broader wilderness context. Anyone planning a trip to paddle on or near Nangmagvik Lake should be prepared for a fully self-sufficient expedition in a remote high-arctic environment, with no services or infrastructure beyond the Polar Bear cabin. Prospective visitors should contact Parks Canada's Aulavik National Park office for current regulations, permit requirements, and logistical guidance well in advance of any planned trip.