We humans may spend most of our time on land, but we live in a saltwater-dominated world, with ocean covering 71 percent of Earth's surface. Geographers divide the globe's ocean into named regions, and the smallest of these is the Arctic Ocean.
Even the smallest of the world's oceans is impressively vast. Stretching for about 5.4 million square miles (8.7 million kilometers), the Arctic Ocean measures about 150 percent larger than North America. It's located at the polar region of the Northern Hemisphere and is almost completely surrounded by the continents of Europe, Asia and North America. Frigid conditions keep the Arctic Ocean partly covered in ice throughout the year and entirely covered in winter, although rising global temperatures have led to increased melting of this Arctic sea ice.
The Arctic Ocean is not only ranked the smallest in size (it's 10 times smaller than the Pacific Ocean), it's also the shallowest. The average ocean depth, according to the National Oceanic and Atmospheric Administration, is 2.3 miles (3.7 kilometers), or about 12,100 feet. The Arctic Ocean's average depth, meanwhile, is much shallower — around 0.65 miles (1.04 kilometers), or 3,407 feet. That's like water sloshing in a kiddie pool when compared to the deepest regions of the Pacific Ocean, which have been measured to around 6.85 miles (11 kilometers), or 36,200 feet, deep.
The relatively small size and depth of the Arctic Ocean have led some to resist classifying it as an ocean, instead referring to it as part of the Atlantic Ocean called the Arctic Mediterranean Sea or simply the Arctic Sea. Seas are considered smaller parts of oceans that are partially enclosed by land.
It may seem unusual that some scientists would challenge whether a body of water is an ocean, but debate around the world's oceans extends beyond the Arctic. Historically, the global community has recognized four oceans: the Atlantic, Pacific, Indian and Arctic Oceans. In 2000, the International Hydrographic Organization (IHO), added a fifth: The Southern Ocean. This ocean, also called The Antarctic Ocean, encircles Antarctica and makes up the southernmost waters on Earth, below the 60-degree south latitude.
The addition of the Southern Ocean, while generally accepted, has not yet been ratified because not all members of the IHO have officially accepted the parameters defining the Southern Ocean as a fifth ocean. So how many oceans are there — four or five? For now, the surest answer may be one since, technically, all the world's oceans are in fact connected as a single, vast body of salt water.