Arctic Ocean

I

Introduction

Arctic Ocean, body of water variously identified as the smallest of five world oceans or as a virtually landlocked arm of the Atlantic Ocean. The Arctic Ocean extends south from the North Pole to the shores of Europe, Asia, and North America.

II

Boundaries and Size

The surface waters of the Arctic Ocean mingle with those of the Pacific Ocean through the Bering Strait, by way of a narrow and shallow channel, which has a depth of about 55 m (180 ft) and a width of about 65 km (40 mi). More importantly, the Arctic waters mix with those of the Atlantic Ocean across a system of submarine sills (shallow ridges) that span the great distances from Scotland to Greenland and from Greenland to Baffin Island at depths of about 500 to 700 m (1,640 to 2,300 ft). Except for the channels to the Atlantic and Pacific, the entire ocean is landlocked, surrounded by Russia, Norway, Greenland, Canada, and Alaska. Emptying into the Arctic Ocean are the Ob, Yenisey, and Lena rivers in Asia and the Mackenzie, Coppermine, and Back rivers in North America. The total surface area of the Arctic Ocean, including its major subdivisions—the North Polar Sea (the main portion), the Norwegian Sea, the North Sea, and the Barents Sea—is about 14 million sq km (5.4 million sq mi).

III

Structural Features

Approximately one-third of the Arctic Ocean is underlain by continental shelf, which includes a broad shelf north of Eurasia and the narrower shelves of North America and Greenland. Seaward of the continental shelves lies the Arctic Basin proper, which is subdivided into a set of three parallel ridges and four basins (also known as deeps). These features have only been discovered and explored since the late 1940s. The Lomonosov Ridge, the major ridge, cuts the North Polar Sea almost in half, extending as a submarine bridge 1,700 km (1,060 mi) from Siberia to the north-western tip of Greenland. Parallel to it are two shorter ridges: the Alpha Ridge on the North American side, defining the Canada and Makarov basins, and the Mid-Ocean Ridge on the Eurasian side, defining the Nansen and Fram basins. The average depth of the Arctic Ocean is only about 1,500 m (4,900 ft) because of the vast shallow expanses on the continental shelves. The deepest point in the Arctic Ocean is 5,450 m (17,880 ft).

IV

Islands

The islands of the Arctic Ocean lie on the continental shelves. To the north-east of Norway lies the archipelago of Svalbard (formerly known as Spitsbergen); to the east are Franz Josef Land, Novaya Zemlya, Severnaya Zemlya, the New Siberian Islands, and Wrangel Island, all of which are located north of Russia. The numerous islands of the Canadian Archipelago, including the Queen Elizabeth Islands, Victoria Island, and Baffin Island, extend north and east from the Canadian mainland to Greenland, the largest island of the Arctic Ocean.