Centered approximately on the North Pole, the Arctic Ocean is the smallest of the world's oceans, covering about 4,732,000 square miles. Maximum depth is 18,050 feet. The ocean is divided into two nearly equal basins: the Eurasia and the Amerasia. The Lomonosov Ridge extends from northeastern Greenland to central Siberia and separates the basins. The Arctic Ocean is surrounded by the landmasses of Eurasia, North America, and Greenland, and is unlike the other three oceans because of the perennial ice cover. The extent of sea ice is seasonal between 60°N and 75°N latitude, but above 75°N it is relatively permanent. Ice cover reduces energy exchange with the atmosphere, resulting in reduced precipitation and cold temperatures.

A unique feature of the ice fields of the Arctic Ocean was the discovery in 1946 of large-sized ice islands. One of the first major ice islands covered an area of more than 300 square miles. In later years, ice islands were extensively tracked to determine current movement. They were also used as scientific research sites for the study of polar meteorology and oceanography.¹