The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about 106,400,000 square kilometres (41,100,000 sq mi), it covers approximately twenty percent of the Earth's surface and about twenty-six percent of its water surface area. The first part of its name refers to Atlas of Greek mythology, making the Atlantic the "Sea of Atlas".
The oldest known mention of "Atlantic" is in The Histories of Herodotus around 450 BC (Hdt. 1.202.4): Atlantis thalassa (Greek: Ἀτλαντὶς θάλασσα; English: Sea of Atlas); Another name historically used was the ancient term Ethiopic Ocean, derived from Ethiopia, whose name was sometimes used as a synonym for all of Africa and thus for the ocean. Before Europeans discovered other oceans, the term "ocean" itself was synonymous with the waters beyond the Strait of Gibraltar that we now know as the Atlantic. The Greeks believed this ocean to be a gigantic river encircling the world.
The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between the Americas to the west, and Eurasia and Africa to the east. As one component of the interconnected global ocean, it is connected in the north to the Arctic Ocean (which is sometimes considered a sea of the Atlantic), to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, and the Southern Ocean in the south. (Other definitions describe the Atlantic as extending southward to Antarctica.) The equator subdivides it into the North Atlantic Ocean and South Atlantic Ocean.
The Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea and Barents Sea. To the east, the boundaries of the ocean proper are Europe; the Strait of Gibraltar (where it connects with the Mediterranean Sea – one of its marginal seas – and, in turn, the Black Sea) and Africa.
In the southeast, the Atlantic merges into the Indian Ocean. The 20° East meridian, running south from Cape Agulhas to Antarctica defines its border. Some authorities show it extending south to Antarctica, while others show it bounded at the 60° parallel by the Southern Ocean.
In the southwest, the Drake Passage connects it to the Pacific Ocean. The man-made Panama Canal links the Atlantic and Pacific. Besides those mentioned, other large bodies of water adjacent to the Atlantic are the Caribbean Sea; the Gulf of Mexico; Hudson Bay; the Arctic Ocean; the Mediterranean Sea; the North Sea; the Baltic Sea and the Celtic Sea.
Covering approximately 22% of Earth's surface, the Atlantic is second in size to the Pacific. With its adjacent seas, it occupies an area of about 106,400,000 square kilometres (41,100,000 sq mi); without them, it has an area of 82,400,000 square kilometres (3.18E+7 sq mi). The land that drains into the Atlantic covers four times that of either the Pacific or Indian oceans. The volume of the Atlantic with its adjacent seas is 354,700,000 cubic kilometers (85,100,000 cu mi) and without them 323,600,000 cubic kilometres (77,640,000 cu mi).
The average depth of the Atlantic, with its adjacent seas, is 3,339 metres (10,955 ft); without them it is 3,926 metres (12,881 ft). The greatest depth, 8,605 metres (28,232 ft), is in the Puerto Rico Trench. The Atlantic's width varies from 2,848 kilometres (1,770 mi) between Brazil and Sierra Leone to over 6,400 km (4,000 mi) in the south.
On average, the Atlantic is the saltiest major ocean; surface water salinity in the open ocean ranges from 33 to 37 parts per thousand (3.3 - 3.7%) by mass and varies with latitude and season. Evaporation, precipitation, river inflow and sea ice melting influence surface salinity values. Although the salinity values are just north of the equator (because of heavy tropical rainfall), in general the lowest values are in the high latitudes and along coasts where large rivers enter. Maximum salinity values occur at about 25° north and south, in subtropical regions with low rainfall and high evaporation.
Surface water temperatures, which vary with latitude, current systems, and season and reflect the latitudinal distribution of solar energy, range from below −2 °C (28.4 °F). Maximum temperatures occur north of the equator, and minimum values are found in the polar regions. In the middle latitudes, the area of maximum temperature variations, values may vary by 7-8 °C (12-15 °F).
The Atlantic Ocean consists of four major water masses. The North and South Atlantic central waters make up the surface. The sub-Antarctic intermediate water extends to depths of 1,000 metres (3,300 ft). The North Atlantic Deep Water reaches depths of as much as 4,000 metres (13,000 ft). The Antarctic Bottom Water occupies ocean basins at depths greater than 4,000 meters.
Within the North Atlantic, ocean currents isolate the Sargasso Sea, a large elongated body of water, with above average salinity. The Sargasso Sea contains large amounts of seaweed and is also the spawning ground for both the European eel and the American eel.
The Coriolis effect circulates North Atlantic water in a clockwise direction, whereas South Atlantic water circulates counter-clockwise. The south tides in the Atlantic Ocean are semi-diurnal; that is, two high tides occur during each 24 lunar hours. In latitudes above 40° North some east-west oscillation occurs.
Climate is influenced by the temperatures of the surface waters and water currents as well as winds. Because of the ocean's great heat retention capacity, maritime climates are more moderate and have less extreme seasonal variations than inland climates. Precipitation can be approximated from coastal weather data and air temperature from water temperatures.
The oceans are the major source of the atmospheric moisture that is obtained through evaporation. Climatic zones vary with latitude; the warmest zones stretch across the Atlantic north of the equator. The coldest zones are in high latitudes, with the coldest regions corresponding to the areas covered by sea ice. Ocean currents influence climate by transporting warm and cold waters to other regions. The winds that are cooled or warmed when blowing over these currents influence adjacent land areas.
The Gulf Stream and its northern extension towards Europe, the North Atlantic Drift, for example, warms the atmosphere of the British Isles and north-western Europe, and the cold water currents contribute to heavy fog off the coast of eastern Canada (the Grand Banks of Newfoundland area) and Africa's north-western coast. In general, winds transport moisture and air over land areas. Hurricanes develop in the southern part of the North Atlantic Ocean.
The Atlantic Ocean appears to be the second youngest of the five oceans. Apparently it did not exist prior to 130 million years ago, when the continents that formed from the breakup of the ancestral super continent, Pangaea, were drifting apart from seafloor spreading. The Atlantic has been extensively explored since the earliest settlements along its shores.
The Vikings, the Portuguese, and the Spaniards were the most famous among early explorers. After Columbus, European exploration rapidly accelerated, and many new trade routes were established.
As a result, the Atlantic became and remains the major artery between Europe and the Americas (known as transatlantic trade). Scientific explorations include the Challenger expedition, the German Meteor expedition, Columbia University's Lamont-Doherty Earth Observatory and the United States Navy Hydrographic Office.
- In 1000, the Icelander, Leif Ericson was the first European to discover North America's Atlantic coast, including Vinland. The Norse discovery was documented in the 13th century Icelandic Sagas and was corroborated by recent L'Anse aux Meadows archeological evidence.
- In 1003, Thorfinnr Karlsefni led an attempted Viking settlement in North America but was driven off by the natives.
- In 1004, Snorri Thorfinnsson was the first European born on the American continent.
- In 1419 and 1427, Portuguese navigators reached Madeira and Azores, respectively.
- From 1415 to 1488, Portuguese navigators sailed along the Western African coast, reaching the Cape of Good Hope.
- In 1492, Christopher Columbus landed somewhere in The Bahamas.
- In 1500, Pedro Álvares Cabral reached Brazil.
- In 1524, Italian explorer Giovanni da Verrazzano discovered the United States of America east coast.
- In 1764 William Harrison (the son of John Harrison) sailed aboard the HMS Tartar, with the H-4 time piece. The voyage became the basis for the invention of the global system of Longitude.
- In 1858, Cyrus West Field laid the first transatlantic telegraph cable (it quickly failed).
- In 1865 Brunel's ship the SS Great Eastern laid the first successful transatlantic telegraph cable .
- On April 15, 1912 the RMS Titanic sank after hitting an iceberg with a loss of more than 1,500 lives.
- 1914-1918, the First Battle of the Atlantic took place.
- In 1919, the American NC-4 became the first fixed-wing aircraft (seaplane) to cross the Atlantic (though it made a couple of landings on islands and the sea along the way, and taxied several hundred miles).
- Later in 1919, a British aeroplane piloted by Alcock and Brown made the first non-stop transatlantic flight, from Newfoundland to Ireland.
- In 1921, the British were the first to cross the North Atlantic in an airship.
- In 1922, Sacadura Cabral and Gago Coutinho were the first to cross the South Atlantic in an airship.
- In 1927, Charles Lindbergh made the first solo non-stop transatlantic flight in an aircraft (between New York City and Paris).
- In 1932, Amelia Earhart became the first female to make a solo flight across the Atlantic
- 1939-1945, the Second Battle of the Atlantic. Nearly 3,700 Allied ships were sunk at a cost of 783 German U-boats.
- In 1952, Ann Davison was the first woman to single-handedly sail the Atlantic Ocean.
- In 1975, Fons Oerlemans crossed the Atlantic in 82 days, starting from Safi (Morocco) to Trinidad and Tobago, on a selfmade raft.
- In 1980, Gérard d'Aboville was the first man to cross the Atlantic Ocean rowing.
- In 1984, Five Argentines sail in a 10 meters long raft made from tree trunks named Atlantis from Canary Islands and after 52 days 3,000 miles (4,800 km) journey arrived to Venezuela in an attempt to prove travelers from Africa may have crossed the Atlantic before Christopher Columbus.
- In 1994, Guy Delage was the first man to allegedly swim across the Atlantic Ocean (with the help of a kick board, from Cape Verde to Barbados).
- In 1998, Benoît Lecomte was the first man to swim across the northern Atlantic Ocean without a kick board, stopping for only one week in the Azores.
- In 1999, after rowing for 81 days and 4,767 kilometres (2,962 mi), Tori Murden became the first woman to cross the Atlantic Ocean by rowboat alone when she reached Guadeloupe from the Canary Islands.