The Arctic Ocean is the smallest and shallowest of the Earth’s five major oceans. Almost completely surrounded by Eurasia and North America, it is partly covered by sea ice throughout the year (and almost completely in winter). It exists in a polar climate: winter features continuous darkness (polar night), profound cold (to-51°C) but stable, clear weather conditions; the brief (typically 3 months) summer features continuous daylight (known as the midnight sun), cool temperatures (to +10 °C) damp, foggy weather, and weak cyclones with rain or snow.
The Arctic Ocean’s surface temperature is fairly constant, near the freezing point of seawater. Sea ice forms when the upper 100–150 meters of ocean water cools to the −1.8°C. Sea ice floats on the ocean's surface and is the dominant surface type of ice throughout the year in the Arctic Basin. It is relatively thin, generally less than 4 metres (13 feet), with thicker ridges. At its maximum extent, in March, Arctic sea ice covers about 15 million km² (5.8 million sq mi).
Winds and ocean currents cause the sea ice to move. Generally speaking, these motions carry sea ice from the Russian side of the Arctic Ocean into the Atlantic Ocean through the area east of Greenland, while they cause the ice on the North American side to rotate clockwise, sometimes for many years. The Arctic basin is also variously frequented by vast ice floes, pack ice, drifting ice, icebergs and ice islands. This environment makes year-round exploration and production impossible, and reliable operational windows for drill ships and floating platforms extremely difficult to predict or achieve. The challenge is to extend the operating season for drill ships and floating platforms by creating systems to enable the vessels to safely remain on station in the presence of ice, thus reducing downtime and improving the efficiency of Arctic operations.