Short answers, pulled from the story.
The Arctic Ocean spans approximately 14,060,000 square kilometers, making it the smallest and shallowest of the world's five oceanic divisions. It is also the coldest, with an average depth of 1,038 meters and a coastline 45,390 kilometers long.
The Arctic Ocean has the lowest average salinity of the five major oceans because of low evaporation, heavy freshwater inflow from rivers and streams, and limited connection and outflow to surrounding saltier waters. Great rivers including the Ob, Yenisei, Lena, and Mackenzie feed a low-salinity top layer that floats on denser deep water.
Fridtjof Nansen made the first nautical crossing of the Arctic Ocean during the Fram Expedition from 1893 to 1896. The first surface crossing was led by Wally Herbert in 1969 by dog sled from Alaska to Svalbard, and the submarine USS Nautilus made the first nautical transit of the North Pole in 1958.
Arctic sea ice mean extent has declined at a current rate of 12.85 percent per decade since 1980, from a winter average of 15,600,000 square kilometers. In September 2012 the ice extent reached a record minimum, diminished by 49 percent against the 1979 to 2000 average.
The Arctic Ocean's political dead zone near its center may hold 25 percent or more of the world's undiscovered oil and gas resources. The Siberian Shelf is the largest continental shelf in the world and holds large oil and gas reserves, and the Lomonosov Ridge may contain up to 10 billion barrels of oil.
Research suggests the Arctic may become ice-free in the summer for the first time in human history by 2040. The Arctic region is currently warming twice as fast as the rest of the planet, and reduced sea ice lowers the planet's average albedo in a positive feedback loop.
The United States, Russia, Canada, Norway, and Denmark are involved in a mounting dispute over the political dead zone near the center of the Arctic Ocean. On the 16th of July 2015 those same five nations signed a declaration to keep fishing vessels out of a 1.1 million square mile zone near the North Pole.