The North Pole lies not on land but on water: the Arctic Ocean. It is permanently covered by ice, although the size of the sea ice shrinks dramatically in summer months as the ice melts and stretches of water open up. The South Pole lies on the continent of Antarctica, a huge, mountainous landmass, much of it covered by a permanent ice cap almost three kilometres (about 10,000 feet) thick in some places. It is the coldest place in the world. In winter, the waters of the Southern Ocean surrounding the continent are covered with floating pack ice and icebergs.

Arctic Ocean

Much of the Arctic Ocean is covered with a thick layer of floating ice all year round. At its edges, rafts of broken ice, called pack ice, drift in the freezing cold waters. These are pieces of ice that are constantly being broken up and crushed together by the movement of the water. During the summer, some of the ice cracks and melts, forming waterways and large stretches of water.

Southern Ocean

The Southern Ocean surrounds the continent of Antarctica. More than half of this ocean freezes each winter. Icebergs, which break off from ice shelves pushed out from the Antarctic ice sheet into the sea, float amongst the pack ice. The East Wind Current flows anticlockwise around Antarctica’s shores. Further north, the vast Antarctic Circumpolar Current flows in the opposite direction.

Icebergs

An iceberg is a large piece of floating ice. About 90% of it is underwater. Most Arctic icebergs have broken off glaciers that have formed on the Arctic island of Greenland and crashed into the sea. Many are cone-shaped. Antarctic icebergs break off from the ice shelf and so are often flat-topped.