Atlantic Ocean
Introduction
Background
The Atlantic Ocean is the second largest of the world's five oceans (after the Pacific Ocean, but larger than the Indian Ocean, Southern Ocean, and Arctic Ocean). The Kiel Canal (Germany), Oresund (Denmark-Sweden), Bosporus (Turkey), Strait of Gibraltar (Morocco-Spain), and the Saint Lawrence Seaway (Canada-US) are important strategic access waterways.The decision by the International Hydrographic Organization in the spring of 2000 to delimit a fifth world ocean, the Southern Ocean, removed the portion of the Atlantic Ocean south of 60 degrees south latitude.
Visit the Definitions and Notes page to view a description of each topic.
Geography
Location
body of water between Africa, Europe, the Arctic Ocean, the Americas, and the Southern Ocean
Geographic coordinates
0 00 N, 25 00 W
Map references
Political Map of the World
Area
total: 85.133 million sq km
note: includes Baffin Bay, Baltic Sea, Black Sea, Caribbean Sea, Davis Strait, Denmark Strait, part of the Drake Passage, Hudson Bay, Hudson Strait, Gulf of Mexico, Labrador Sea, Mediterranean Sea, North Sea, almost all of the Scotia Sea, and other tributary water bodies
Area - comparative
about 7.5 times the size of the US
Coastline
111,866 km
Climate
tropical cyclones (hurricanes) develop off the coast of Africa near Cabo Verde and move westward into the Caribbean Sea; hurricanes can occur from May to December but are most frequent from August to November
Ocean volume
ocean volume: 310,410,900 cu km
percent of World Ocean total volume: 23.3%
Major ocean currents
clockwise North Atlantic Gyre consists of the northward flowing, warm Gulf Stream in the west, the eastward flowing North Atlantic Current in the north, the southward flowing cold Canary Current in the east, and the westward flowing North Equatorial Current in the south; the counterclockwise South Atlantic Gyre composed of the southward flowing warm Brazil Current in the west, the eastward flowing South Atlantic Current in the south, the northward flowing cold Benguela Current in the east, and the westward flowing South Equatorial Current in the north
Bathymetry
continental shelf: The continental shelf (see Figure 1), a rather flat area of the sea floor adjacent to the coast that gradually slopes down from the shore to water depths of about 200 m (660 ft). Dimensions can vary: they may be narrow or nearly nonexistent in some places or extend for hundreds of miles in others. The waters along the continental shelf are usually productive in both plant and animal life, both from sunlight and nutrients from ocean upwelling and terrestrial runoff. The passive margins of the Atlantic Ocean provide for wide continental shelves in North America, Northwest Europe, and the southern coast of South America. The following are examples of features found on the continental shelf of the Atlantic Ocean.
Blake Plateau (Figure 5)
Celtic Shelf (Figure 2)
Dogger Bank (Figure 2)
Flemish Cap (Figure 2)
Falkland Plateau (Figure 3)
Grand Banks of Newfoundland (Figure 2)
Great Bahama Bank (Figure 5)
Little Bahama Bank (Figure 5)
Tunisian Plateau (Figure 4)
Yacatan Shelf (Figure 5)
continental slope: The continental slope (see Figure 1) is where the ocean bottom drops off more rapidly until it meets the deep-sea floor (abyssal plain) at about 3,200 m (10,500 ft) water depth. The deep waters of the continental slope are characterized by cold temperatures, low light conditions, and very high pressures. Sunlight does not penetrate to these depths, having been absorbed or reflected in the water above. The continental slope can be indented by submarine canyons, often associated with the outflow of major rivers. Another feature of the continental slope are alluvial fans or cones of sediments carried downstream to the ocean by major rivers and deposited down the slope. The following are examples of features found on the continental slope of the Atlantic Ocean.
Amazon Cone (Figure 3)
Congo Fan (Figure 3)
Hudson Canyon (Figure 5)
Mississippi Fan (Figure 5)
abyssal plains: The abyssal plains (see Figure 1), at depths of over 3,000 m (10,000 ft) and covering 70% of the ocean floor, are the largest habitat on earth. Sunlight does not penetrate to the sea floor, making these deep, dark ecosystems less productive than those along the continental shelf. Despite their name, these “plains” are not uniformly flat; they are interrupted by features like hills, valleys, and seamounts. The following are examples of features found on the abyssal plains of the Atlantic Ocean.
Angola Basin (Figure 3)
Agulhas Basin (Figure 3)
Argentine Basin (Figure 3)
Brazil Basin (Figure 3)
Canary Basin (Figure 2)
Cape Basin (Figure 3)
Colombia Basin (Figure 2)
Labrador Basin (Figure 2)
Mexico Basin (Figure 2)
Newfoundland Basin (Figure 2)
North American Basin (Figure 2)
Venezuela Basin (Figure 2)
West European Basin (Figure 2)
mid-ocean ridge: The mid-ocean ridge (see Figure 1), rising up from the abyssal plain, is an underwater mountain range, over 64,000 km (40,000 mi) long, rising to an average depth of 2,400 m (8,000 ft). Mid-ocean ridges form at divergent plate boundaries where two tectonic plates are moving apart and new crust is created by magma pushing up from the mantle. Tracing their way around the global ocean, this system of underwater volcanoes forms the longest mountain range on Earth. Fracture Zones are linear transform faults that develop perpendicular to the line of the mid-ocean ridge which can offset the ridge line and divide it into segments.The Charlie-Gibbs Fracture Zone displaces the mid-ocean ridge 350 km to the west separating the Mid-Atlantic Ridge from the Reykjanes Ridge. The Romanche Fracture Zone, located near the Equator, offsets the Mid-Atlantic Ridge 900 km and is considered the dividing line between the North and South Atlantic Oceans. The following are examples of mid-ocean ridges found on the floor of the Atlantic Ocean.
East Mediterranean Ridge (Figure 4)
Mid-Atlantic Ridge (Figures 2, 3)
Reykjanes Ridge (Figure 2)
seamounts: Seamounts (see Figure 1) are submarine mountains at least 1,000 m (3,300 ft) high formed from individual volcanoes on the ocean floor. They are distinct from the plate-boundary volcanic system of the mid-ocean ridges, because seamounts tend to be circular or conical. A circular collapse caldera is often centered at the summit, evidence of a magma chamber within the volcano. Flat topped seamounts are known as guyots. Long chains of seamounts are often fed by "hot spots" in the deep mantle. These hot spots are associated with stationary plumes of molten rock rising from deep within the Earth's mantle. These hot spot plumes melt through the overlying tectonic plate as it moves and supplies magma to the active volcanic island at the end of the chain of volcanic islands and seamounts. The following are examples of seamounts found on the floor of the Atlantic Ocean.
Bermuda Rise (Figure 2)
Cape Verde Plateau (Figure 2)
New England Seamounts (Figure 2)
Rio Grande Plateau (Figure 3)
Rockall Plateau (Figure 2)
ocean trenches: Ocean trenches (see Figure 1) are the deepest parts of the ocean floor and are created by the process of subduction. Trenches form along convergent boundaries where tectonic plates are moving toward each other, and one plate sinks (is subducted) under another. The location where the sinking of a plate occurs is called a subduction zone. Subduction can occur when oceanic crust collides with and sinks under (subducts) continental crust resulting in volcanic, seismic, and mountain-building processes. Subduction can also occur in the convergence of two oceanic plates where one will sink under the other and in the process create a deep ocean trench. Subduction processes in oceanic-oceanic plate convergence also result in the formation of volcanoes. Over millions of years, the erupted lava and volcanic debris pile up on the ocean floor until a submarine volcano rises above sea level to form a volcanic island. Such volcanoes are typically strung out in chains called island arcs. As the name implies, volcanic island arcs, which closely parallel the trenches, are generally curved. The following are examples of ocean trenches found on the floor of the Atlantic Ocean.
Cayman Trench (Caribbean Sea) (Figure 2)
Hellenic Trench (Mediterranean Sea) (Figure 4)
Puerto Rico Trench (Figure 2); note - deepest point in the Atlantic Ocean
South Sandwich Trench (South Atlantic) (Figure 3)
atolls: Atolls are the remains of dormant volcanic islands. In warm tropical oceans, coral colonies establish themselves on the margins of the island. Then, over time, the high elevation of the island collapses and erodes away to sea level leaving behind an outline of the island in the form of the fringing coral reef. The resulting low island is typified by the coral reef surrounding a low elevation of sand and coral above sea level with an interior shallow lagoon. Often times the remaining dry land is broken into a ring of islets. Some lagoons can be hundreds of square kilometers. It may take as long as 300,000 years for an atoll formation to occur. Guyots are submerged atoll structures, which explains why they are flat topped seamounts. The following are examples of atolls found in the Atlantic Ocean
Rocas Atoll (Brazil); note - the only atoll in the South Atlantic
Elevation
highest point: sea level
lowest point: Puerto Rico Trench -8,605 m
mean depth: -3,646 m
ocean zones: Composed of water and in a fluid state, the oceans are delimited differently than the solid continents. Oceans are divided into three zones based on depth and light level. Although some sea creatures depend on light to live, others can do without it. Sunlight entering the water may travel about 1,000 m into the oceans under the right conditions, but there is rarely any significant light beyond 200 m.
The upper 200 m (656 ft) of oceans is called the euphotic, or "sunlight," zone. This zone contains the vast majority of commercial fisheries and is home to many protected marine mammals and sea turtles. Only a small amount of light penetrates beyond this depth.
The zone between 200 m (656 ft) and 1,000 m (3,280 ft) is usually referred to as the "twilight" zone, but is officially the dysphotic zone. In this zone, the intensity of light rapidly dissipates as depth increases. Such a minuscule amount of light penetrates beyond a depth of 200 m that photosynthesis is no longer possible.
The aphotic, or "midnight," zone exists in depths below 1,000 m (3,280 ft). Sunlight does not penetrate to these depths and the zone is bathed in darkness.
Natural resources
oil and gas fields, fish, marine mammals (seals and whales), sand and gravel aggregates, placer deposits, polymetallic nodules, precious stones
Natural hazards
icebergs common in Davis Strait, Denmark Strait, and the northwestern Atlantic Ocean from February to August and have been spotted as far south as Bermuda and the Madeira Islands; ships subject to superstructure icing in extreme northern Atlantic from October to May; persistent fog can be a maritime hazard from May to September; hurricanes (May to December)
Geography - note
major chokepoints include the Dardanelles, Strait of Gibraltar, access to the Panama and Suez Canals; strategic straits include the Strait of Dover, Straits of Florida, Mona Passage, The Sound (Oresund), and Windward Passage; the Equator divides the Atlantic Ocean into the North Atlantic Ocean and South Atlantic Ocean
Environment
Environment - current issues
endangered marine species include the manatee, seals, sea lions, turtles, and whales; unsustainable exploitation of fisheries (over fishing, bottom trawling, drift net fishing, discards, catch of non-target species); pollution (maritime transport, discharges, offshore drilling, oil spills); municipal sludge pollution off eastern US, southern Brazil, and eastern Argentina; oil pollution in Caribbean Sea, Gulf of Mexico, Lake Maracaibo, Mediterranean Sea, and North Sea; industrial waste and municipal sewage pollution in Baltic Sea, North Sea, and Mediterranean Sea
Marine fisheries
the Atlantic Ocean fisheries are the second most important in the world accounting for 26.4%, or 21,063,495 mt, of the global catch in 2019; of the seven regions delineated by the Food and Agriculture Organization in the Atlantic basin, the most important include the following:
Northeast Atlantic region (Region 27) is the fourth most important in the world producing 10.2% of the global catch or 8,116,507 mt in 2019; the region encompasses the waters north of 36º North latitude and east of 40º West longitude with the major producers including Norway (3,528,240 mt), Russia (1,044,153 mt), Iceland (933,019 mt), UK (823,669 mt), and Denmark (641,927 mt); the region includes the historically important fishing grounds of the North Sea, the Baltic Sea, and the Atlantic waters between Greenland, Iceland, and the British Isles; the principal catches include Atlantic cod, haddock, saithe (pollock), Blue Whiting, herring, and mackerel; not all fish caught are for human consumption, half of fish catches in the North Sea are processed as fish oil or fish meal, which are used in animal fodder
Eastern Central Atlantic region (Region 34) is the second most important Atlantic fishery, and sixth largest in the world producing more than 6.8% of the global catch or 5,397,726 mt in 2019; the region encompasses the waters between 36º North and 6º South latitude and east of 40º West longitude off the west coast of Africa with the major producers including Morocco (1,419,872 mt), Mauritania (705,850 mt), Senegal (472,571 mt), Nigeria (451,768 mt), Ghana (303,001 mt), Cameroon (265,969 mt), and Sierra Leone (200,000 mt); the principal catches include pilchard, sardinellas, shad, and mackerel
Northwest Atlantic region (Region 21) is the third most important Atlantic fishery and eighth in the world producing 2% of the global catch and 1,679,512 mt in 2019; it encompasses the waters north of 35º North latitude and west of 42º West longitude including the important fishing grounds over the continental shelf of North America such as the Grand Banks, the Georges Bank, and the Flemish Cap, as well as Baffin Bay with the major producers including the US (927,777 mt), Canada (615,651 mt), and Greenland (179,990 mt); the principal catches include sea scallops, prawns, lobster, herring, and menhaden
Mediterranean and Black Sea region (Region 37) is a minor fishing region representing 1.7% or 1,385,190 mt of the world’s total capture in 2019; the region encompasses all waters east of the Strait of Gibraltar with the major producers including Turkey (686,650 mt), Italy (281,212 mt), Tunisia (129,325 mt), Spain (119,759 mt), and Russia (72,279 mt); the principal catches include European anchovy, European pilchard, Gobies, and clams
Regional fisheries bodies: Commission for the Conservation of Southern Bluefin Tuna, Fishery Committee for the Eastern Central Atlantic, Fisheries Committee for the West Central Gulf of Guinea, General Fisheries Commission for the Mediterranean, International Commission for the Conservation of Atlantic Tunas, International Council for the Exploration of the Seas, Northwest Atlantic Fisheries Organization, North Atlantic Salmon Conservation Organization, North East Atlantic Fisheries Commission, Southeast Atlantic Fisheries Organization, Western Central Atlantic Fishery Commission
Climate
tropical cyclones (hurricanes) develop off the coast of Africa near Cabo Verde and move westward into the Caribbean Sea; hurricanes can occur from May to December but are most frequent from August to November
Government
Country name
etymology: name derives from the Greek description of the waters beyond the Strait of Gibraltar, Atlantis thalassa, meaning "Sea of Atlas"
Economy
Economic overview
The Atlantic Ocean provides some of the world's most heavily trafficked sea routes, between and within the Eastern and Western Hemispheres. Other economic activity includes the exploitation of natural resources, e.g., fishing, dredging of aragonite sands (The Bahamas), and production of crude oil and natural gas (Caribbean Sea, Gulf of Mexico, and North Sea).
Transportation
Icebreakers
North Atlantic
Canada: one PC 3 or 4 class medium icebreaker
France: one PC 5 or 6 class light icebreaker
Germany: one PC 5 or 6 class light icebreaker
US: one PC 3 or 4 class medium icebreaker, and one PC 5 or 6 class light icebreaker
Baltic
Denmark: three PC 5 or 6 class light icebreakers
Estonia: two PC 5 or 6 class light icebreakers
Finland: seven PC 3 or 4 class medium icebreakers, and two PC 5 or 6 class light icebreakers
Latvia: one PC 5 or 6 class light icebreaker
Russia: 22 PC 3 or 4 class medium icebreakers, and five PC 5 or 6 class light icebreakers
Sweden: four PC 3 or 4 class medium icebreakers
Great Lakes/St Lawrence Seaway
Canada: one PC 3 or 4 class medium icebreaker, ten PC 5 or 6 class light icebreakers
Mediterranean
Italy: one PC 5 or 6 class light icebreaker
South Atlantic
Argentina: one PC 5 or 6 class light icebreaker
UK (Falkland Islands): one PC 3 or 4 class medium icebreaker
South Africa: one PC 5 or 6 class light icebreaker
note: the ships are listed by Polar Class (PC) vessel: PC 1 - year-round operation in all polar waters (ice thickness >3 m); PC 2 - year-round operation in moderate multi-year ice conditions (ice thickness up to 3 m); PC 3 - year-round operation in second-year ice which may include multi-year ice inclusions (ice thickness up to 2.5 m); PC 4 - year-round operation in thick first-year ice which may include old ice inclusions (ice thickness up to 120 cm); PC 5 - year-round operation in medium first-year ice which may include old ice inclusions (ice thickness up to 70-120 cm); PC 6 - summer/autumn operation in medium first-year ice which may include old ice inclusions (ice thickness up to 30-70 cm)
Ports and terminals
major seaport(s): Alexandria (Egypt), Algiers (Algeria), Antwerp (Belgium), Barcelona (Spain), Buenos Aires (Argentina), Casablanca (Morocco), Colon (Panama), Copenhagen (Denmark), Dakar (Senegal), Gdansk (Poland), Hamburg (Germany), Helsinki (Finland), Las Palmas (Canary Islands, Spain), Le Havre (France), Lisbon (Portugal), London (UK), Marseille (France), Montevideo (Uruguay), Montreal (Canada), Naples (Italy), New Orleans (US), New York (US), Oran (Algeria), Oslo (Norway), Peiraiefs or Piraeus (Greece), Rio de Janeiro (Brazil), Rotterdam (Netherlands), Saint Petersburg (Russia), Stockholm (Sweden)
Transportation - note
Kiel Canal and Saint Lawrence Seaway are two important waterways; significant domestic commercial and recreational use of Intracoastal Waterway on central and south Atlantic seaboard and Gulf of Mexico coast of US
Military and Security
Maritime threats
the International Maritime Bureau reports the territorial and offshore waters in the Niger Delta and Gulf of Guinea remain a very high risk for piracy and armed robbery of ships; in 2021, there were 34 reported incidents of piracy and armed robbery at sea in the Gulf of Guinea region; although a significant decrease from the total number of 81 incidents in 2020, it included the one hijacking and three of five ships fired upon worldwide; while boarding and attempted boarding to steal valuables from ships and crews are the most common types of incidents, almost a third of all incidents involve a hijacking and/or kidnapping; in 2021, 57 crew members were kidnapped in seven separate incidents in the Gulf of Guinea, representing 100% of kidnappings worldwide; Nigerian pirates in particular are well armed and very aggressive, operating as far as 200 nm offshore; the Maritime Administration of the US Department of Transportation has issued a Maritime Advisory (2022-001 - Gulf of Guinea-Piracy/Armed Robbery/Kidnapping for Ransom) effective 4 January 2022, which states in part, "Piracy, armed robbery, and kidnapping for ransom continue to serve as significant threats to US-flagged vessels transiting or operating in the Gulf of Guinea;” South American ports in Brazil and Colombia, as well as Caribbean ports in Mexico and Haiti continue to be affected by the crime of armed robbery against ships with 15 incidents reported in 2021 compared to 17 in 2020 with most of these occurring while berthed or anchored
Transnational Issues
Disputes - international
some maritime disputes (see littoral states)