The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest, and shallowest of the world's five major oceanic divisions. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea or simply the Arctic Sea, classifying it as one of the mediterranean seas of the Atlantic Ocean. Alternatively, the Arctic Ocean can be seen as the northernmost lobe of the all-encompassing World Ocean.

Almost completely surrounded by Eurasia and North America, the Arctic Ocean is partly covered by sea ice throughout the year (and almost completely in winter). The Arctic Ocean's temperature and salinity vary seasonally as the ice cover melts and freezes; its salinity is the lowest on average of the five major oceans, due to low evaporation, heavy freshwater inflow from rivers and streams, and limited connection and outflow to surrounding oceanic waters with higher salinities. The summer shrinking of the ice has been quoted at 50%. The National Snow and Ice Data Center (NSIDC) use satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years.

Geography

According to the International Hydrographic Organization, the limits of the Arctic Ocean proper (that is, excluding the seas within the Ocean) are (see the map):

• A great circle line running from Cape Morris Jesup, the northernmost point of Greenland ( ) to the northernmost point of Spitsbergen (south of which line lies the Greenland Sea).
• Parallel 80° North to North East Land (Nordaustlandet).
• The north shore of Nordaustlandet to its easternmost point, Cape Leigh Smith ( ).
• A line running from Cape Leigh Smith to Cape Kohlsaat, the easternmost point of Franz Josef Land ( , south of which line lies the Barents Sea].
• A line running from Cape Kohlsaat to Cape Molotov (Arctic Cape), the northernmost point of Komsomolets Island ( , south of which line lies the Kara Sea).
• A line running from Arctic Cape to the northernmost point of Kotelny Island ( , south of which line lies the Laptev Sea).
• A line running from the northernmost point of Kotelny Island to the northernmost point of Wrangel Island ( , south of which line lies the East Siberian Sea).
• A line running from the northernmost point of Wrangel Island to Point Barrow, the northernmost point of Alaska ( , south of which line lies the Chuckchi Sea).
• A line running from Point Barrow to Cape Land's End on Prince Patrick Island, Northwest Territories ( , south of which line lies the Beaufort Sea).
• The northwest coast of Prince Patrick Island north to Cape Leopold M'Clintock, its northernmost point ( ).
• A line running from Cape Leopold M'Clintock to Cape Murray on Brock Island ( ).
• The northwest coast of Brock Island north to its northernmost point ( ).
• A line running from the northernmost point of Brock Island to Cape Mackay on Borden Island, its westernmost point ( ).
• The northwest coast of Borden Island north to Cape Malloch ( , the northernmost point of the Northwest Territories).
• A line running from Cape Malloch to Cape Isachsen on Ellef Ringnes Island, Nunavut, its northwestern most point ( ).
• A line running from Cape Isachsen to the northwestern most point of Meighen Island ( ).
• A line running from the northwestern most point of Meighen Island to Cape Stallworthy on Axel Heiberg Island, its northernmost point ( ).
• A line running from Cape Stallworthy to Cape Colgate on Ellesmere Island, its westernmost point ( ).
• The north coast of Ellesmere Island north to Cape Columbia, its northernmost point ( ).
• A line running from Cape Columbia to Cape Morris Jesup (south of which line lies the Lincoln Sea).