The surface of the planet is approximately 71% water and contains (5) five oceans, including the Arctic, Atlantic, Indian, Pacific and Southern. For many years only (4) four oceans were officially recognized, and then in the spring of 2000, the International Hydrographic Organization established the Southern Ocean and determined its limits. Those limits include all water below 60 degrees south, and some of it, like the Arctic Ocean, is frozen.
The following are detailed explanations of the five oceans of the world.
- The Pacific ocean, this is the largest of these oceans, covering 63,784,077 sq miles (165,200,000 km²). It fills the area between the western coastline of the Americas, the eastern coastlines of Asia and Africa, and is capped to the North and South by the Arctic and Antarctic regions. In part because of the numerous tropical islands of East Asia, the Pacific boasts the longest total shoreline, some 84,300 miles (135,663 km). It also holds the deepest point on the earth’s sea floor, the Challenger Deep in the Marianas Trench, near the island of Guam. At close to 11,000 meters below sea level, or almost 7 miles, this crevice was first sounded in 1875 by the HMS Challenger. The Pacific was named by Portuguese explorer Ferdinand Magellan, who set sail from Spain in 1519 to find a westerly route to the Spice Islands around the southernmost tip of South America.
- The Atlantic Ocean is the second-largest ocean in the world with an area of 106,400,000 square kilometers. It is bordered by the Americas in the west and Africa and Europe in the east. The Atlantic Ocean consists of the Mediterranean Sea, Caribbean Sea, Baltic Sea, and the Gulf of Mexico. Like the Pacific Ocean, the Atlantic Ocean also reaches out to the Arctic Ocean in the north and the Antarctic Ocean in the south. Up to the 15th century, the Indian Ocean and the eastern Atlantic Ocean were the only known voyaged seas in the world. The ocean is home to a lot of marine species, including the sperm whale which is the largest living toothed animal. The equator divides the ocean into the North Atlantic Ocean and the South Atlantic Ocean. The area north of the equator, between Africa and South America, is referred to as Central Atlantic. The water in this part is very different from the waters in the northern part, which is between Europe and North America. The Atlantic Ocean is known to be the saltiest. The processes of evaporation, precipitation, river inflow, and sea ice melting are the major contributors to salinity. The water in North Atlantic circulates in a clockwise direction, whereas the water in the South Atlantic circulates in an anti-clockwise direction. This is due to the Coriolis Effect. This ocean is also the second youngest among all oceans. Before 30 million years ago, it did not even exist.
- The Indian Ocean is the third-largest ocean in the world. Covering an area of around 73,556,000 square kilometers, the Indian Ocean has been home to a rich variety of humankind throughout world history. The Indian Ocean is bordered by the eastern coast of Africa, the shores of the Middle East, and India in the north. It is separated from the Pacific Ocean by south East Asia and Australia. The Indian Ocean is also rich in exotic plant and animal species. Around 20% of all the water on the Earth’s surface is in the Indian Ocean. It is the youngest of all the major oceans on the earth. It is a major sea route that connects Africa, the Middle East, and East Asia with the Americas and Europe. Around 40% of the world’s offshore oil production is known to come from the Indian Ocean. The different bordering countries largely exploit the beach sands that contain a rich amount of heavy minerals.
- Southern ocean, until the mid-20th Century, the waters surrounding Antarctica were generally considered to be extensions of the adjoining oceans. But in 2000, members of the International Hydrographic Organization almost unanimously agreed to identify these southernmost waters as the Southern Ocean. Although its definite boundaries are yet to be determined, below 60°S latitude is generally accepted, giving it an area of 7,848,299 sq miles (20,327,000 km²), and making it the fourth largest of the Earth’s oceans. Joining waters of the southern Pacific, Atlantic, and Indian Oceans with a persistent easterly current, the frigid Southern Ocean has a great influence on the Earth’s weather patterns.
- Arctic ocean, 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.