[4] Established 1 January 1959, and consisting of 112,811 ha (1,128.11 km2; 435.57 sq mi)[2] it is rated Category IV by the International Union for Conservation of Nature.

Due to the frozen nature of Hudson Bay, there is a severe seasonal lag until June, especially compared to more continental areas such as Fairbanks despite much sunshine and perpetual twilight at night.

Cold extremes are severe, but in line with many areas even farther south in Canada's interior.

The sanctuary's habitat consists of three main types, water, unvegetated land, and moist or wet vegetated tundra.

[8] This can be further broken down as dry heath, gravel ridge, intertidal zone, moss carpet, scrub willow, and sedge meadow.