The Arctic is dominated by the Arctic Ocean and vast treeless plain called the tundra. Arctic is mostly consisted of ice-covered seas unlike Antarctica which is an ice-covered continent.

The Arctic Ocean
The Arctic Ocean which covers approximately 5 million square miles(13 million square kilometres), makes up about two thirds of the Arctic region. East of the island of Greeland, the Arctic Ocean connects with the Atlantic Ocean. West of Greenland the Arctic flows through Baffin Bay, Davis Strait, and shallow outlets between the northern islands of Canada.

The Arctuc Ocean joins the Pacific Ocean through the Bering Straits, which separates Soviet Siberia from Alaska. Although its extent varies from summer to winter, ice covers the Arctic Ocean year-round, making navigation frequently difficult and dangerous. From October to June the ocean is completely ice-locked, and only submarines can cross it completely by passing under the ice. At times, icebergs break off the end of glaciers in Greenland and Canada. Many float south into the shipping lanes of Atlantic Ocean and create hazards to navigation.

The Tundra The tundra begins on the land area of the Arctic about where the tree line ends. When the summer sun melts the ice and snow cover, the Arctic tundra becomes a rich green living carpet of plants. But beneath a thin layer of soil lies ground that is always frozen. This permafrost forms whenever the temperature of the ground stays continuously below the freezing point (32°F, 0°C), for two or more years. Most of Greenland, much of Alaska, half of Canada and the Soviet Union, and parts of Scandinavia, Mongolia, and Northeast China are affected by permafrost. Its greatest recorded thickness -- 4900 feet (1500 metres) -- is in Siberia. Not all the land in the Arctic region is covered by tundra. Rocky, mountainous islands quite different from the flat tundra tundra are scattered around the Arctic Ocean. Greenland is almost completely covered by a large ice sheet, with mountains ringing its coast.