An ocean (from Greek Greek , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical ancient Greek literature and the New Testament of Ὠκεανὸς, "okeanos" Oceanus In classical antiquity, Oceanus was believed to be the world-ocean, which the ancient Romans and Greeks considered to be an enormous river encircling the world. Strictly speaking, Oceanus was the ocean-stream at the Equator in which floated the habitable hemisphere (oikoumene οἰκουμένη). In Greek mythology, this world-ocean was^[1]) is a major body of saline water Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5%. This means that every kilogram, or every litre, of seawater has approximately 35 grams of dissolved salts (mostly, but not entirely, the ions of sodium chloride: Na+, Cl−). The average density of seawater at the ocean surface is 1.025, and a principal component of the hydrosphere A hydrosphere in physical geography describes the combined mass of water found on, under, and over the surface of a planet. Approximately 71% of the Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet,[note 6] or by its Latin name, Terra.[note 7]'s surface In mathematics, specifically in topology, a surface is a two-dimensional topological manifold. The most familiar examples are those that arise as the boundaries of solid objects in ordinary three-dimensional Euclidean space R3 — for example, the surface of a ball. On the other hand, there are surfaces, such as the Klein bottle, that cannot be (~3.61 X 10¹⁴ m²) is covered by ocean, a continuous body of water The World Ocean, world ocean, or global ocean is the interconnected system of the earth's oceanic waters, and comprises the bulk of the hydrosphere that is customarily divided into several principal oceans and smaller seas A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, the term refers to a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean. It is also used sometimes to describe a large saline lake that lacks a natural outlet, such as the Caspian Sea.

More than half of this area is over 3,000 metres The metre , symbol m, is the base unit of length in the International System of Units (SI). Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole, its definition has been periodically refined to reflect growing knowledge of metrology. Since 1983, it is defined as the distance travelled by light in a (9,800 ft) deep. Average oceanic salinity Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates. Salinity in Australian English and North American English may also refer to the salt content of soil is around 35 parts per thousand In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. Scientists estimate that 230,000 marine life forms of all types are currently known, but the total could be up to 10 times that number.^[2]

Overview

Though generally described as several 'separate' oceans, these waters comprise one global, interconnected body of salt water sometimes referred to as the World Ocean The World Ocean, world ocean, or global ocean is the interconnected system of the earth's oceanic waters, and comprises the bulk of the hydrosphere or global ocean.^[3][4] This concept of a continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean. It covers a wide range of topics, including marine organisms and ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamics; plate tectonics and the geology of the sea floor; and fluxes of various chemical substances and.^[5]

The major oceanic divisions are defined in part by the continents A continent is one of several large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents – they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia, various archipelagos Archipelagos can be found isolated in bodies of water; or with a large land mass may neighbour them. For example, Scotland has more than 700 islands surrounding its mainland. Archipelagos are often volcanic, forming along island arcs generated by subduction zones or hotspots, but there are many other processes involved in their construction,, and other criteria. These divisions are (in descending order of size):

• Pacific Ocean The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east, which separates Asia Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.6% of the Earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population. During the 20th century Asia's population nearly quadrupled and Australia For at least 40,000 years before European settlement in the late 18th century, Australia was inhabited by indigenous Australians, who belonged to one or more of the roughly 250 language groups. After sporadic visits by fishermen from the immediate north and discovery by Dutch explorers in 1606, Australia's eastern half was claimed by the British from the Americas The Americas, or America, are lands in the Western hemisphere, also known as the New World, comprising the continents of North America and South America with their associated islands and regions. America may be ambiguous in English, as it is more commonly used to refer to the United States of America. The Americas cover 8.3% of the Earth's total
• Atlantic Ocean The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about 106,400,000 square kilometres , 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 the Atlas of Greek mythology, making the Atlantic the ", which separates the Americas from Eurasia Eurasia is a large landmass covering about 52,990,000 km2 or about 10.6% of the Earth's surface (36.2% of the land area). Often considered a single continent, Eurasia comprises the traditional continents of Europe and Asia (with Eurasia being a portmanteau of the two), concepts which date back to classical antiquity and the borders for which are and Africa Africa is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area. With a billion people (as of 2009, see table) in 61 territories, it accounts for about 14.72% of the world's human population
• Indian Ocean The Indian Ocean is the third largest of the world's oceanic divisions, covering about 20% of the water on the Earth's surface. It is bounded on the north by the Indian subcontinent; on the west by East Africa; on the east by Indochina, the Sunda Islands, and Australia; and on the south by the Southern Ocean . It is the only ocean to be named, which washes upon southern Asia Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.6% of the Earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population. During the 20th century Asia's population nearly quadrupled and separates Africa and Australia
• Southern Ocean The Southern Ocean, also known as the Great Southern Ocean, the Antarctic Ocean and the South Polar Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions. This ocean zone is where cold,, which, unlike other oceans, has no landmass separating it from other oceans and is therefore sometimes subsumed as the southern portions of the Pacific, Atlantic, and Indian Oceans, which encircles Antarctica Antarctica (pronounced /ænˈtɑrktɪkə/ ) is Earth's southernmost continent, underlying the South Pole. It is situated in the Antarctic region of the southern hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14.0 million km2 (5.4 million sq mi), it is the fifth-largest continent in area after and covers much of the Antarctic The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence. The region covers some 20% of the Southern Hemisphere, of which 5.5% (1
• Arctic Ocean The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest, and shallowest of the world's five major oceanic divisions. The International Hydrographic Organization recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea or simply the Arctic Sea, classifying, sometimes considered a sea A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, the term refers to a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean. It is also used sometimes to describe a large saline lake that lacks a natural outlet, such as the Caspian Sea of the Atlantic, which covers much of the Arctic The Arctic is the region around the Earth's North Pole, opposite the Antarctic region around the South Pole. The Arctic includes the Arctic Ocean (which overlies the North Pole) and parts of Canada, Greenland (a territory of Denmark), Russia, the United States (Alaska), Iceland, Norway, Sweden and Finland and washes upon northern North America North America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific Ocean; South America lies to the southeast and Eurasia

The Pacific and Atlantic may be further subdivided by the equator An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass. The capitalized term Equator refers to the Earth's equator into northern The word north is related to the Old High German nord, both descending from the Proto-Indo-European unit ner-, meaning "left" . (Presumably a natural primitive description of its concept is "to the left of the rising sun".) and southern By Western convention, the bottom side of a map is south; the southern direction has azimuth or bearing of 180° portions. Smaller regions of the oceans are called seas A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, the term refers to a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean. It is also used sometimes to describe a large saline lake that lacks a natural outlet, such as the Caspian Sea, gulfs Headlands and bays are often found together on the same stretch of coastline. A bay is surrounded by land on three sides, whereas a headland is surrounded by water on three sides. Headlands are characterized by high, breaking waves, rocky shores, intense erosion, and steep sea cliffs. Bays generally have less wave activity than the water outside, bays A bay is an area of water mostly surrounded or otherwise demarcated by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. It can also be an inlet in a lake or pond, straits A strait or straits is a narrow, navigable channel of water that connects two larger navigable bodies of water. It most commonly refers to a channel of water that lies between two land masses, but it may also refer to a navigable channel through a body of water that is otherwise not navigable, for example because it is too shallow, or because it and other names.

Geologically, an ocean is an area of oceanic crust Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium. It is thinner than continental crust, or sial, generally less than 10 kilometers thick, however it is denser, having a mean density of about 3.3 grams per cubic covered by water. Oceanic crust is the thin layer of solidified volcanic basalt Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey that covers the Earth's mantle The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiated by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core. Earth's mantle is a rocky shell about 2,890 km thick that. Continental crust The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in contrast to the oceanic crust, called sima due to its is thicker but less dense. From this perspective, the earth has three oceans: the World Ocean, the Caspian Sea The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of 371,000 km2 (143,200 sq mi) (Not including Garabogazköl Aylagy) and a volume of 78,200 km3 (18,800 cu mi). It is in an endorheic basin (it has no outflows) and is bounded by^{[citation needed]}, and Black Sea The Black Sea is an inland sea bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and Aegean Seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects it to the Aegean Sea region of the Mediterranean. These waters. The latter two were formed by the collision of Cimmeria The Cimmerian Plate is an ancient tectonic plate that comprises parts of present-day Anatolia, Iran, Afghanistan, Tibet, Indochina and Malaya regions. The Cimmerian Plate was formerly part of the ancient supercontinent of Pangaea. Pangaea was shaped like a vast "C", facing east, and inside of the "C" was the Paleo-Tethys Ocean with Laurasia Laurasia was a supercontinent that most recently existed as a part of the split of the Pangaea supercontinent in the late Mesozoic era. It was located in the north after Pangaea split into two followed by Gondwanaland in the south. It included most of the landmasses which make up today's continents of the northern hemisphere, chiefly Laurentia (. The Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by Africa, and on the east by the Levant. The sea is technically a part of the Atlantic Ocean, although it is usually identified as a completely separate is at times a discrete ocean, because tectonic plate movement Plate tectonics is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, developed in the 1960s has repeatedly broken its connection to the World Ocean through the Strait of Gibraltar The Strait of Gibraltar is a narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Spain in Europe from Morocco in Africa. The name comes from Gibraltar, which in turn originates from the Arabic Jebel Tariq (meaning "Tariq's mountain"), albeit the Arab name for the Strait is Bab el-Zakat or "Gate of. The Black Sea is connected to the Mediterranean through the Bosporus The Bosphorus or Bosporus , also known as the Istanbul Strait (Turkish: İstanbul Boğazı), is a strait that forms part of the boundary between Europe and Asia. It is one of the Turkish Straits, along with the Dardanelles. The world's narrowest strait used for international navigation, it connects the Black Sea with the Sea of Marmara (which is, but the Bosporus is a natural canal cut through continental rock some 7,000 years ago, rather than a piece of oceanic sea floor like the Strait of Gibraltar.

Despite their names, smaller landlocked bodies of saltwater that are not connected with the World Ocean, such as the Aral Sea, are actually salt lakes.

Ocean and life

The ocean has a significant effect on the biosphere. Oceanic evaporation, as a phase of the water cycle, is the source of most rainfall, and ocean temperatures determine climate and wind patterns that affect life on land. Life within the ocean evolved 3 billion years prior to life on land. Both the depth and distance from shore strongly influence the amount and kinds of plants and animals that live there.^[6]

Physical properties

The area of the World Ocean is 361×10⁶ km² (139×10⁶ mi²)^[7] Its volume is approximately 1.3 billion cubic kilometres (310 million cu mi).^[8] This can be thought of as a cube of water with an edge length of 1,111 kilometres (690 mi). Its average depth is 3,790 metres (12,430 ft), and its maximum depth is 10,923 metres (6.787 mi)^[7] Nearly half of the world's marine waters are over 3,000 metres (9,800 ft) deep.^[4] The vast expanses of deep ocean (anything below 200 metres (660 ft) cover about 66% of the Earth's surface.^[9] This does not include seas not connected to the World Ocean, such as the Caspian Sea.

The total mass of the hydrosphere is about 1,400,000,000,000,000,000 metric tons (1.5×10¹⁸ short tons) or 1.4×10²¹ kg, which is about 0.023 percent of the Earth's total mass. Less than 3 percent is freshwater; the rest is saltwater, mostly in the ocean.

Color

A common misconception is that the oceans are blue primarily because the sky is blue. In fact, water has a very slight blue color that can only be seen in large volumes. While the sky's reflection does contribute to the blue appearance of the surface, it is not the primary cause.^[10] The primary cause is the absorption by the water molecules' nuclei of red photons from the incoming light, the only known example of color in nature resulting from vibrational, rather than electronic, dynamics.^[11]

Glow

Sailors and other mariners have reported that the ocean often emits a visible glow, or luminescence, which extends for miles at night. In 2005, scientists announced that for the first time, they had obtained photographic evidence of this glow.^[12] It may be caused by bioluminescence.^[13][14][15]

Exploration

Ocean travel by boat dates back to prehistoric times, but only in modern times has extensive underwater travel become possible.

The deepest point in the ocean is the Mariana Trench, located in the Pacific Ocean near the Northern Mariana Islands. Its maximum depth has been estimated to be 10,971 metres (35,994 ft) (plus or minus 11 meters; see the Mariana Trench article for discussion of the various estimates of the maximum depth.) The British naval vessel, Challenger II surveyed the trench in 1951 and named the deepest part of the trench, the "Challenger Deep". In 1960, the Trieste successfully reached the bottom of the trench, manned by a crew of two men.

Much of the ocean bottom remains unexplored and unmapped. A global image of many underwater features larger than 10 kilometres (6.2 mi) was created in 1995 based on gravitational distortions of the nearby sea surface.^{[citation needed]}

Regions and depths

Oceanographers divide the ocean into regions depending on physical and biological conditions of these areas. The pelagic zone includes all open ocean regions, and can be divided into further regions categorized by depth and light abundance. The photic zone covers the oceans from surface level to 200 metres down. This is the region where photosynthesis can occur and therefore is the most biodiverse. Since plants require photosynthesis, life found deeper than this must either rely on material sinking from above (see marine snow) or find another energy source; hydrothermal vents are the primary option in what is known as the aphotic zone (depths exceeding 200 m). The pelagic part of the photic zone is known as the epipelagic. The pelagic part of the aphotic zone can be further divided into regions that succeed each other vertically according to temperature.

The mesopelagic is the uppermost region. Its lowermost boundary is at a thermocline of 12 °C (54 °F), which, in the tropics generally lies at 700–1,000 metres (2,300–3,300 ft). Next is the bathypelagic lying between 10-4 °C (43 °F), typically between 700–1,000 metres (2,300–3,300 ft) and 2,000–4,000 metres (6,600–13,000 ft) Lying along the top of the abyssal plain is the abyssalpelagic, whose lower boundary lies at about 6,000 metres (20,000 ft). The last zone includes the deep trenches, and is known as the hadalpelagic. This lies between 6,000–11,000 metres (20,000–36,000 ft) and is the deepest oceanic zone.

Along with pelagic aphotic zones there are also benthic aphotic zones. These correspond to the three deepest zones of the deep-sea. The bathyal zone covers the continental slope down to about 4,000 metres (13,000 ft). The abyssal zone covers the abyssal plains between 4,000 and 6,000 m. Lastly, the hadal zone corresponds to the hadalpelagic zone which is found in the oceanic trenches. The pelagic zone can also be split into two subregions, the neritic zone and the oceanic zone. The neritic encompasses the water mass directly above the continental shelves, while the oceanic zone includes all the completely open water. In contrast, the littoral zone covers the region between low and high tide and represents the transitional area between marine and terrestrial conditions. It is also known as the intertidal zone because it is the area where tide level affects the conditions of the region.

Geology

The ocean floor spreads from mid-ocean ridges where two plates adjoin. Where two plates move towards each other, one plate subducts under another plate (oceanic or continental) leading to an oceanic trench.

Climate effects

Ocean currents greatly affect the Earth's climate by transferring heat from the tropics to the polar regions, and transferring warm or cold air and precipitation to coastal regions, where winds may carry them inland. Surface heat and freshwater fluxes create global density gradients that drive the thermohaline circulation part of large-scale ocean circulation. It plays an important role in supplying heat to the polar regions, and thus in sea ice regulation. Changes in the thermohaline circulation are thought to have significant impacts on the Earth's radiation budget. Insofar as the thermohaline circulation governs the rate at which deep waters reach the surface, it may also significantly influence atmospheric carbon dioxide concentrations.

For a discussion of the possibilities of changes to the thermohaline circulation under global warming, see shutdown of thermohaline circulation.

It is often stated that the thermohaline circulation is the primary reason that the climate Western Europe is so temperate. An alternate hypothesis claims that this is largely incorrect, and that Europe is warm mostly because it lies downwind of an ocean basin, and because atmospheric waves bring warm air north from the subtropics.^[16][17]

The Antarctic Circumpolar Current encircles that continent, influencing the area's climate and connecting currents in several oceans.

One of the most dramatic forms of weather occurs over the oceans: tropical cyclones (also called "typhoons" and "hurricanes" depending upon where the system forms).

Biology

Lifeforms native to oceans include:

• Radiata
• Fish
• Cetacea such as whales, dolphins and porpoises,
• Cephalopods such as octopus and squid
• Crustaceans such as lobsters, clams, shrimp and krill
• Marine worms
• Plankton
• Echinoderms such as brittle stars, starfish, sea cucumbers and sand dollars

Economy

The oceans are essential to transportation: most of the world's goods move by ship between the world's seaports.

Oceans are also the major supply source for the fishing industry. Some of the more major these are shrimp, fish, crabs and lobster.

Ancient oceans

Continental drift continually reconfigures the oceans, joining and splitting bodies of water.^{[citation needed]} Ancient oceans include:

• Bridge River Ocean, the ocean between the ancient Insular Islands and North America.
• Iapetus Ocean, the southern hemisphere ocean between Baltica and Avalonia.
• Panthalassa, the vast world ocean that surrounded the Pangaea supercontinent.
• Rheic Ocean
• Slide Mountain Ocean, the ocean between the ancient Intermontane Islands and North America.
• Tethys Ocean, the ocean between the ancient continents of Gondwana and Laurasia.
• Khanty Ocean, the ocean between Baltica and Siberia.
• Mirovia, the ocean that surrounded the Rodinia supercontinent.
• Paleo-Tethys Ocean, the ocean between Gondwana and the Hunic terranes.
• Poseidon Ocean
• Proto-Tethys Ocean
• Pan-African Ocean, the ocean that surrounded the Pannotia supercontinent.
• Superocean, the ocean that surrounds a global supercontinent.
• Ural Ocean, the ocean between Siberia and Baltica.

Extraterrestrial oceans

See also Extraterrestrial liquid water

Earth is the only known planet with liquid water on its surface and is certainly the only one in our own solar system. However, liquid water is thought to be present under the surface of the Galilean moons Europa and, with less certainty, Callisto and Ganymede. Geysers have been found on Saturn's moon Enceladus, though these may not involve bodies of liquid water. Other icy moons may have once had internal oceans that have now frozen, such as Triton. The planets Uranus and Neptune may also possess large oceans of liquid water under their thick atmospheres, though their internal structure is not well understood.

There is currently much debate over whether Mars once had an ocean in its northern hemisphere, and over what happened to it; recent findings by the Mars Exploration Rover mission indicate Mars had long-term standing water in at least one location, but its extent is not known.

Astronomers believe that Venus had liquid water and perhaps oceans in its very early history. If they existed, all later vanished via resurfacing.

Liquid hydrocarbons are thought to be present on the surface of Titan, though lakes may be a more accurate term. The Cassini-Huygens space mission initially discovered only what appeared to be dry lakebeds and empty river channels, suggesting that Titan had lost what surface liquids it might have had. Cassini's more recent fly-by of Titan offers radar images that strongly suggest hydrocarbon lakes near the colder polar regions. Titan is thought to have a subterranean water ocean under the ice and hydrocarbon mix that forms its outer crust.

Beyond the solar system, the planet Gliese 581 c is at the right distance from its sun to support liquid surface water. However, its greenhouse effect would make it too hot for oceans to exist on the surface. On Gliese 581 d the greenhouse effect may bring temperatures suitable for surface oceans. Astronomers dispute whether HD 209458 b has water vapour in its atmosphere. Gliese 436 b is believed to have "hot ice." Neither of these planets are cool enough for liquid water—but if water molecules exist there, they are also likely to be found on planets at a suitable temperature.^[18] GJ 1214 b, detected by transit, found evidence that this planet has oceans made of exotic form of ice VII, making up 75% of all the planet's mass.^[19]

Culture

The original concept of "ocean" goes back to notions of Mesopotamian and Indo-European mythology, imagining the world to be encircled by a great river. Okeanos in Greek, reflects the ancient Greek observation that a strong current flowed off Gibraltar and their subsequent assumption that it was a great river. (Compare also Samudra from Hindu mythology and Jörmungandr from Norse mythology.) The world was imagined to be enclosed by a celestial ocean above the heavens, and an ocean of the underworld below.

Artworks which depict maritime themes are known as marine art, a term which particularly applies to common styles of European painting of the 17th to 19th centuries.

See also

• Earthdive
• International Maritime Organization
• Law of the Sea
• Marginal sea
• Marine biology
• Marine debris
• Marine pollution
• Mediterranean sea
• Ocean acidification
• Oceanography
• Pelagic zone
• Polar seas
• Sea
• Sea level and sea level rise
• Sea salt
• Sea state
• Seawater
• Seven Seas
• Water
• World Ocean Atlas
• World Ocean Day

References

1. ^ Ὠκεανός, Henry George Liddell, Robert Scott, A Greek-English Lexicon, at Perseus project
2. ^ Drogin, Bob (October 24, 2003). "Census of Marine Life maps an ocean of species". http://www.latimes.com/new/la-na-fish2-2009aug02,0,5785256.story?page=1&track=ntothtml. Retrieved August 18, 2009.
3. ^ "Ocean". The Columbia Encyclopedia. 2002. New York: Columbia University Press
4. ^ ^{a b} "Distribution of land and water on the planet". UN Atlas of the Oceans
5. ^ Spilhaus first=Athelstan F. (July 1942). Maps of the whole world ocean. 32 (3). American Geographical Society).. pp. 431–5.
6. ^ Biology: Concepts & Connections. Chapter 34: The Biosphere: An Introduction to Earth's Diverse Environment. (sec 34.7)
7. ^ ^{a b} ,"The World's Oceans and Seas". Encarta. http://encarta.msn.com/media_461547746/The_World's_Oceans_and_Seas.html.
8. ^ Qadri, Syed (2003). "Volume of Earth's Oceans". The Physics Factbook. http://hypertextbook.com/facts/2001/SyedQadri.shtml. Retrieved 2007-06-07.
9. ^ Drazen, Jeffrey C.. "Deep-Sea Fishes". School of Ocean Earth Science and Technology, University of University of Hawaiʻi at M?noa. http://www.soest.hawaii.edu/oceanography/faculty/drazen/fishes.htm. Retrieved 2007-06-07.
10. ^ BAD PHYSICS: Misconceptions spread by K-6 Grade School Textbooks
11. ^ "Why is water blue?". Journal Chemical Education. 1994. p. 612. http://www.dartmouth.edu/~etrnsfer/water.htm.
12. ^ "Mystery Ocean Glow Confirmed in Satellite Photos". October 4, 2005. http://www.livescience.com/strangenews/051004_sea_glow.html.
13. ^ 11/21/2005, Usa today: A glowing sea, courtesy of algae Quote: "...The water glowed green in the direction of the movement...A: Little microscopic creatures (called Lingulodinium polyedrum) that glow in the dark caused the alluring strange display that night..."
14. ^ 05 October 2005, New Scientist: Sea's eerie glow seen from space Quote: "...The ancient mariners were right. Tales of "milky seas" that glow bluish-white at night and extend as far as the horizon have been spun by sailors for centuries. Now this eerie glow has been spotted from space....The glowing area spanned 15,400 square kilometres (5,900 sq mi), an area the size of Connecticut (Image: Steven D Miller, US Naval Research Laboratory)..."
15. ^ NASA, DAAC Study: The Incredible Glowing Algae Quote: "...Each year, the North Atlantic Ocean announces springtime by producing “blooms” large enough to be seen from space. These explosive increases in microscopic marine algae, called phytoplankton, appear as sudden bright blossoms in satellite imagery..."
16. ^ Seager, R. (2006). "The Source of Europe's Mild Climate"]. American Scientist. http://www.americanscientist.org/issues/feature/2006/4/the-source-of-europes-mild-climate.
17. ^ Rhines and Hakkinen (2003). "Is the Oceanic Heat Transport in the North Atlantic Irrelevant to the Climate in Europe?". ASOF Newsletter. http://www.realclimate.org/Rhines_hakkinen_2003.pdf.
18. ^ Hot "ice" may cover recently discovered planet
19. ^ David A. Aguilar (2009-12-16). "Astronomers Find Super-Earth Using Amateur, Off-the-Shelf Technology". Harvard-Smithsonian Center for Astrophysics. http://www.cfa.harvard.edu/news/2009/pr200924.html. Retrieved January 23, 2010.

• Matthias Tomczak and J. Stuart Godfrey. 2003. Regional Oceanography: an Introduction. (see the site)
• "Origins of the oceans and continents". UN Atlas of the Oceans.

Further reading

• Pope, F. 2009. From eternal darkness springs cast of angels and jellied jewels. in The Times. November 23. 2009 p. 16 - 17.

External links

• Oceans at the Open Directory Project
• National Oceanic and Atmospheric Administration
• Marine forecasts for any ocean point - Buoyweather is a helpful link for marine safety
• Council on Foreign Relations, Interactive Guide to Oceans Governance

Categories: Oceans | Oceanography | Greek loanwords | Coastal and oceanic landforms

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