The smallest ocean is also the planet’s shallow cold cap
The Arctic Ocean is the smallest, shallowest and coldest of Earth's five oceans, spanning about 14 million square kilometres around the North Pole, nearly the size of Antarctica and the only ocean smaller than Russia. Sea ice covers most of it all year and almost all of it every winter.
It reaches south to roughly 60°N, ringed by Eurasia and North America, and its borders follow the seafloor: the narrow Bering Strait facing the Pacific, and the submarine Greenland–Scotland Ridge facing the Atlantic. A few oceanographers prefer the label Arctic Mediterranean Sea, or treat it as almost an estuary of the Atlantic. The Lomonosov Ridge splits the deep basin into the Eurasian Basin, 4,000–4,500 metres deep, and the Amerasian Basin at about 4,000, yet the average depth is only 1,038 metres thanks to broad shelves, including the Siberian Shelf, the largest anywhere and rich in oil and gas.
People reached the North American Arctic at least 17,000 and perhaps 50,000 years ago, crossing the Bering land bridge exposed by low seas. Paleo-Eskimo cultures followed, from the Pre-Dorset and Greenland's Saqqaq to the Dorset, who spread across the region between 500 BC and AD 1500. The Thule tradition, arising near the Bering Strait around 200 BC, eventually covered nearly the whole North American Arctic; its people were the ancestors of the Inuit.
Around 325 BC Pytheas of Massilia described a northern land where the sun set for just three hours and the sea became a congealed substance, probably loose sea ice. Belief in an ice-free Open Polar Sea lingered for centuries; John Barrow of the British Admiralty promoted searches for it from 1818 to 1845. Fridtjof Nansen's Fram made the first nautical crossing between 1893 and 1896, the submarine USS Nautilus transited the pole in 1958, and Wally Herbert's dog-sled team crossed the ice in 1969.
Soviet and later Russian crews have monitored the ocean from drifting ice stations since 1937, carried thousands of kilometres by the floes. In World War II, Allied convoys supplying Soviet northern ports fought German air and naval forces. Scandinavian Airlines opened the first commercial flights over the ocean, between Los Angeles and Copenhagen, in 1954, and the icebreaker Arktika made the first surface voyage through the pole in 1977.
Source: Arctic Ocean
