The Arctic Realm, as here defined, are those terrestrial areas where the average temperature for the warmest month is below 10℃. It therefore includes all of the Arctic Circle including almost all of Greenland, the northern coast of Siberia and northern Scandinavia, northern Alaska, and northern Canada including the high arctic islands. The focal point is of course the Arctic Ocean, the smallest, shallowest and coldest of the world’s oceans and in many ways little more than an estuary of the North Atlantic. It consists of a roughly circular basin generally taken to include the Barents, Beaufort, Chuckchi, East Siberian, Greenland, Kara, Laptev and White seas, along with Hudson Bay and other tributary bodies of water. The latter is connected to the Pacific Ocean by the Bering Strait and to the Atlantic through the Greenland and Labrador seas. The Arctic Realm is bordered by the Nearctic and Palearctic realms to the south, and has affinities to both in terms of its fauna.