At 5,400,025 sq. miles (13,986,000 km²), the Arctic is the smallest and shallowest of the five Oceans, and falls mostly within the Arctic Circle. It is surrounded by the Eurasian and North American continents, and includes Hudson Bay and the North and Barents Seas. For most of the year, these seas are a mass of ice often hundreds of feet thick; even during the brief summer months ice can make the Arctic Ocean impassable, and it wasn’t known until modern times that there is little solid ground in the most northern reaches of the Earth. Nonetheless, its icy landscape has been inhabited since ancient times by the hardy ancestors of the Inuit of North America, the Sami of Scandinavia, and the Nenets of Russia. The great explorers of the 16th-19th Centuries were determined to find passage from the North Atlantic through to the rich shores of Asia in search of spices, silks and opium. The majority of these explorations ended in failure and disaster; but in the 19th and 20th Centuries accurate passage was finally charted through the mostly frozen waters of the Arctic. Learn more about the Artic Ocean.