The Arctic Ocean covers over five million square miles.  It is a little more that one and a half times the size of the United States.     It has an average depth of 3,950 feet with its greatest depth being the Eurasia basin at 17,880 feet.   The Arctic Ocean has 45,389 km of coastline.   It includes the Baffin Bay, Barents Sea, Beaufort Sea, Chukchi Sea, East Siberian Sea, Greenland Sea, Hudson Bay, Hudson Strait, Kara Sea, Laptev Sea, Northwest Passage, as well as other bodies of water.   The climate is polar and the winter brings long days of darkness while the summer brings long days of daylight.     The terrain has many drifting polar icepacks.   The natural resources include oil and gas fields, fish, marine mammals,  and polymetallic nodules, sand and gravel aggregates, and placer deposits.   Its endangered species include walruses and whales.  Its ecosystem is slow to recover from environmental damage or disruption.   Ships need to be cautious of icing from October to May.     Major ports of the Arctic Ocean are Churchill (Canada), Murmansk (Russia), and Prudhoe Bay (US).