An ocean (from Greek Ωκεανός, Okeanos (Oceanus)) is a major body of saline water, and a principal component of the hydrosphere. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Ocean (Ὠκεανός was believed to be the world-ocean in Classical antiquity, which the ancient Romans and Greeks considered to be Seawater is Water from a Sea or Ocean. On average seawater in the world's oceans has a Salinity of about 3 A hydrosphere (from Greek ύδωρ - hydor, " Water " + σφαίρα - sphaira, " Sphere " Approximately 71% of the Earth's surface (an area of some 361 million square kilometers) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 In Mathematics, specifically in Topology, a surface is a Two-dimensional Manifold. Square Kilometre ( US spelling square kilometer) symbol km2, is a decimal multiple of the SI unit of The World Ocean, world ocean, or global ocean is the interconnected system of the Earth 's Oceanic (or marine) Waters This article is about the body of water For other uses see SEA and Seas. More than half of this area is over 3,000 meters (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (ppt) (3. Salinity is the Saltiness or dissolved salt content of a body of Water. In Chemistry, concentration is the measure of how much of a given substance there is mixed with another substance 5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt.
Though generally recognized as several 'separate' oceans, these waters comprise one global, interconnected body of salt water often referred to as the World Ocean or global ocean. The World Ocean, world ocean, or global ocean is the interconnected system of the Earth 's Oceanic (or marine) Waters  This concept of a global ocean as a continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography. Oceanography (from the greek words Ωκεανός meaning Ocean and γράφω meaning to write also called oceanology or  The major oceanic divisions are defined in part by the continents, various archipelagos, and other criteria: these divisions are (in descending order of size) the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean (which is sometimes subsumed as the southern portions of the Pacific, Atlantic, and Indian Oceans), and the Arctic Ocean (which is sometimes considered a sea of the Atlantic). A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions An archipelago (ɑrkəˈpɛləgoʊ is a chain or cluster of Islands The word archipelago literally means "chief Sea " from Italian The Pacific Ocean is the largest of the Earth 's Oceanic divisions The Indian Ocean is the third largest of the world's Oceanic divisions covering about 20% of the water on the Earth 's surface The Southern Ocean, also known as the Great Southern Ocean, the Antarctic Ocean and the South Polar Ocean, comprises the southernmost waters of 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 This article is about the body of water For other uses see SEA and Seas. The Pacific and Atlantic may be further subdivided by the equator into northerly and southerly portions. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the This is about the direction for other uses see North (disambiguation. South is one of Cardinal directions and is opposite to the North. Smaller regions of the oceans are called seas, gulfs, bays and other names. This article is about the body of water For other uses see SEA and Seas. Headlands and bays are two related features of the coastal environment Headlands and bays are two related features of the coastal environment There are also some smaller bodies of saltwater that are on land and not interconnected with the World Ocean, such as the Aral Sea, and the Great Salt Lake – though they may be referred to as 'seas', they are actually salt lakes. The Aral Sea ( Kazakh: Арал Теңізі Aral Tengizi, Orol dengizi Russian: Аральскοе мοре Tajik / Persian: Daryocha-i Great Salt Lake, located in the northern part of the US state of Utah, is the largest salt lake in the western hemisphere the fourth-largest terminal The salt lake or saline lake is a landlocked body of Water which has a concentration of Salts (mostly Sodium chloride) and other minerals significantly
Geologically, an ocean is an area of oceanic crust covered by water. Oceanic crust is the thin layer of solidified volcanic basalt that covers the Earth's mantle where there are no continents. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided From this perspective, there are three oceans today: the World Ocean and the Caspian and Black Seas, the latter two having been formed by the collision of Cimmeria with Laurasia. The Black Sea is an inland Sea bounded by southeastern Europe, the Caucasus and the Anatolian peninsula ( Turkey The Cimmerian Plate is an ancient Tectonic plate that comprises parts of present-day Anatolia, Iran, Afghanistan, Tibet, Indochina Laurasia (lɔˈreɪʃiə lɔˈreɪʒə was a Supercontinent that most recently existed as a part of the split of the Pangaean supercontinent in the late Mesozoic The Mediterranean Sea is very nearly a discrete ocean, being connected to the World Ocean through the Strait of Gibraltar, and indeed several times over the last few million years movement of the African continent has closed the strait off entirely. The Strait of Gibraltar ( Arabic: مضيق جبل طارق Spanish: Estrecho de Gibraltar) is the Strait that connects the Atlantic Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere The Black Sea is connected to the Mediterranean through the Bosporus, but this is in effect 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. The Bosporus or Bosphorus, also known as the Istanbul Strait, (İstanbul Boğazı (Βόσπορος is a Strait that forms the boundary between the Canals are artificial channels for water There are two types of canals water conveyance canals which are used for the conveyance and delivery of water and Waterways Some parts are jello.
The area of the World Ocean is 361 million square kilometers (139 million sq mi), its volume is approximately 1. Seawater is Water from a Sea or Ocean. On average seawater in the world's oceans has a Salinity of about 3 3 billion cubic kilometers (310 million cu mi), and its average depth is 3,790 meters (12,430 ft).  Nearly half of the world's marine waters are over 3,000 meters (9,800 ft) deep.  The vast expanses of deep ocean (anything below 200m) cover about 66% of the Earth's surface.  This does not include seas not connected to the World Ocean, such as 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 total mass of the hydrosphere is about 1. A hydrosphere (from Greek ύδωρ - hydor, " Water " + σφαίρα - sphaira, " Sphere " 4 × 1021 kilograms, which is about 0. 023% of the Earth's total mass. Less than 2% is freshwater; the rest is saltwater, mostly in the ocean. Freshwater is a word that refers to bodies of water such as Ponds lakes rivers and streams containing low concentrations of dissolved Salts and other Total dissolved
A common misconception is that the oceans are blue primarily because the sky is blue. The color of water is a subject of both scientific study and popular misconception 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.  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. 
Travel on the surface of the ocean through the use of boats dates back to prehistoric times, but only in modern times has extensive underwater travel become possible. The National Oceanic and Atmospheric Administration ( NOAA) is a scientific agency within the United States Department of Commerce focused on the conditions of the
The deepest point in the ocean is the Marianas Trench located in the Pacific Ocean near the Northern Mariana Islands. The Mariana Trench (or Mariana's Trench) is the deepest part of the world's Oceans and the deepest location on the surface of the Earth 's The Northern Mariana Islands, officially the Commonwealth of the Northern Mariana Islands (CNMI is a commonwealth in Political union with the United It has a maximum depth of 10,923 meters (35,838 ft) . It was fully surveyed in 1951 by the British naval vessel, "Challenger II" which gave its name to the deepest part of the trench, the "Challenger Deep". The Challenger Deep is the deepest surveyed point in the oceans with a depth of about 11000 metres (about 36000 feet In 1960, the Trieste successfully reached the bottom of the trench, manned by a crew of two men. Design Trieste was designed by the Swiss scientist Auguste Piccard and built in Italy
Much of the bottom of the world's oceans are unexplored and unmapped. A global image of many underwater features larger than 10 kilometers (6 mi) was created in 1995 based on gravitational distortions of the nearby sea surface.
Oceans are divided into numerous regions depending on the physical and biological conditions of these areas. The pelagic zone includes all open ocean regions, and can be subdivided into further regions categorized by depth and light abundance. Any water in the sea that is not close to the bottom is in the pelagic zone. The photic zone covers the oceans from surface level to 200 meters down. The photic zone or euphotic zone ( Greek 'well lit' is the depth of the water in a Lake or Ocean, that is exposed to sufficient Sunlight This is the region where the photosynthesis most commonly occurs and therefore contains the largest biodiversity in the ocean. Since plants can only survive with photosynthesis any life found lower than this must either rely on material floating down from above (see marine snow) or find another primary source; this often comes in the form of hydrothermal vents in what is known as the aphotic zone (all depths exceeding 200m). In the deep ocean marine snow is a continuous shower of mostly organic Detritus falling from the upper layers of the water column A hydrothermal vent is a Fissure in a planet's surface from which geothermally heated Water issues The pelagic part of the photic zone is known as the epipelagic. Any water in the sea that is not close to the bottom is in the pelagic zone. The pelagic part of the aphotic zone can be further divided into regions that succeed each other vertically. The mesopelagic is the uppermost region, with its lowermost boundary at a thermocline of 12°C, which, in the tropics generally lies between 700 and 1,000 m. The mesopelagic ( Greek μέσον middle (also known as the middle pelagic or twilight zone) is a Pelagic zone extending from 200 m (650 ft The thermocline (sometimes metalimnion) is a thin but distinct layer in a large body of water such as an ocean or lake in which temperature changes more rapidly with depth After that is the bathypelagic lying between 10°C and 4°C, or between 700 or 1,000 m and 2,000 or 4,000 m. The bathyal zone or bathypelagic – from Greek βαθύς (bathýs deep – is the Pelagic zone that extends from a depth of 1000 to 4000 Lying along the top of the abyssal plain is the abyssalpelagic, whose lower boundary lies at about 6,000 m. The abyssal zone is the abyssopelagic layer of Pelagic zone that contains the very deep Benthic communities near the bottom of Oceans "Abyss" The final zone falls into the oceanic trenches, and is known as the hadalpelagic. Hadal zone or (trench zone (Greek for "like Hades," in other words "unseen" or Hadopelagic zone is the delineation for the deepest This lies between 6,000 m and 10,000 m and is the deepest oceanic zone.
Along with pelagic aphotics zones there are also benthic aphotic zones, these correspond to the three deepest zones. The benthic zone is the ecological region at the lowest level of a Body of water such as an Ocean or a Lake, including the sediment surface and some sub-surface The bathyal zone covers the continental slope and the rise down to about 4,000 m. The bathyal zone or bathypelagic – from Greek βαθύς (bathýs deep – is the Pelagic zone that extends from a depth of 1000 to 4000 The abyssal zone covers the abyssal plains between 4,000 and 6,000 m. The abyssal zone is the abyssopelagic layer of Pelagic zone that contains the very deep Benthic communities near the bottom of Oceans "Abyss" Lastly, the hadal zone corresponds to the hadalpelagic zone which is found in the oceanic trenches. Hadal zone or (trench zone (Greek for "like Hades," in other words "unseen" or Hadopelagic zone is the delineation for the deepest The pelagic zone can also be split into two subregions, the neritic zone and the oceanic zone. The neritic zone, also called the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the Continental shelf, with a relatively 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. Littoral refers to the coast of an ocean or sea or to the banks of a river lake or estuary It is also known as the intertidal zone because it is the area where tide level affects the conditions of the region.
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). The weather is a set of all the phenomena occurring in a given Atmosphere at a given Time. A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding Ocean currents greatly affect the Earth's climate by transferring warm or cold air and precipitation to coastal regions, where they may be carried inland by winds. An ocean current is continuous directed movement of Ocean water. The Antarctic Circumpolar Current encircles that continent, influencing the area's climate and connecting currents in several oceans. The Antarctic Circumpolar Current ( ACC) is an Ocean current that flows from west to east around Antarctica.
Lifeforms native to oceans include (among others):
The oceans are essential to transportation: most of the world's goods are moved by ship between the world's seaports. The Radiata are the radially symmetric animals of the Eumetazoa subregnum Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two The Order Cetacea (sɪˈteɪʃiə L cetus, whale includes Whales Dolphins and Porpoises Cetus is Whales are marine mammals which are neither Dolphins (ie members of the families Delphinidae or Platanistoidae) nor Porpoises Orcas Dolphins are Marine mammals that are closely related to Whales and Porpoises There are almost forty species of dolphin in seventeen genera. Porpoises are Small Cetaceans of the Family Phocoenidae; they are related to Whales and Dolphins They are distinct from dolphins The cephalopods ( Greek plural (kephalópoda "head-feet" are the Mollusc class Cephalopoda characterized by The Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting Clawed lobsters compose a family ( Nephropidae, sometimes also Homaridae) of large marine Crustaceans Lobsters are economically important as True shrimp are swimming decapod Crustaceans classified in the Infraorder Caridea, found widely around the world in both fresh Any Worm that lives in a marine environment is considered a marine worm. Plankton consist of any drifting Organisms ( Animals Plants Archaea, or Bacteria) that inhabit the Pelagic zone of Krill are a type of Shrimp -like marine Invertebrate animal These small Crustaceans are important organisms of the Zooplankton, particularly Echinoderms (Phylum Echinodermata) are a phylum of marine Animals (including Sea stars) A ship /ʃɪp/ is a large vessel that floats on water Ships are generally distinguished from Boats based on size ||-||-|-||-||-||-||-||-||-|} A port is a facility for receiving Ships and transferring cargo Important ship canals include the Saint Lawrence Seaway, Panama Canal, and Suez Canal. A ship canal is a Canal especially constructed to carry Ocean -going Ships as opposed to Barges Ship canals can be enlarged barge canals The St Lawrence Seaway is the common name for a system of Canals that permits ocean-going vessels to travel from the Atlantic Ocean to the Great Lakes The Panama Canal is a man-made Canal in Panama which joins the The Suez Canal is a Canal in Egypt. Opened in 1869 it allows Water transportation between Europe and Asia without circumnavigation They are also an important source of valuable food items for the fishing industry. The fishing industry includes any industry or activity concerned with taking culturing processing preserving storing transporting marketing or selling fish or fish products Some of these are shrimp, fish, crabs and lobster. True shrimp are swimming decapod Crustaceans classified in the Infraorder Caridea, found widely around the world in both fresh Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Crabs are decapod Crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (βραχύ / brachy Clawed lobsters compose a family ( Nephropidae, sometimes also Homaridae) of large marine Crustaceans Lobsters are economically important as
Continental drift has reconfigured the Earth's oceans, joining and splitting ancient oceans to form the current oceans. Continental drift is the movement of the Earth 's Continents relative to each other Ancient oceans include:
Earth is the only known planet with liquid water on its surface and is certainly the only one in our own solar system. Extraterrestrial liquid water, the presence of Water in its Liquid state is a subject of wide interest because it is a commonly suggested prerequisite for the emergence A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is The Solar System consists of the Sun and those celestial objects bound to it by Gravity. However, liquid water is thought to be present under the surface of the Galilean moons Europa, and, with less certainty, Callisto and Ganymede. The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei. TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as TemplateInfobox Planet.--> Callisto (kəˈlɪstoʊ, or as Greek TemplateInfobox Planet.--> Ganymede (ˈgænɨmiːd, or as Greek Geysers have been found on Enceladus, though these may not involve bodies of liquid water. A geyser is a Hot spring characterized by intermittent discharge of water ejected turbulently and accomplished by a vapour phase TemplateInfobox Planet.--> This article is about the moon of Other icy moons may have once had internal oceans that have now frozen, such as Triton. TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek 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 at this time. Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System.
There is currently much debate over whether Mars once had an ocean of water in its northern hemisphere, and over what happened to it if it did; recent findings by the Mars Exploration Rover mission indicate it had some long-term standing water in at least one location, but its extent is not known. NASA 's Mars Exploration Rover ( MER) Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of
Astronomers believe that Venus had liquid water and perhaps oceans in its very early history. Structure and composition Composition The atmosphere of Venus is composed mainly of Carbon dioxide, along with a small amount of Nitrogen and other If they existed, all trace of them seems to have vanished in later resurfacing. Venus has striking surface characteristics which are as beautiful as they are unusual
Liquid hydrocarbons are thought to be present on the surface of Titan, though it may be more accurate to describe them as "lakes" rather than an "ocean". TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as 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–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its A more recent fly-by of Titan made by Cassini has produced radar images that strongly suggest hydrocarbon lakes near the polar regions where it is colder. Titan is also thought likely to have a subterranean water ocean under the mix of ice and hydrocarbons that forms its outer crust.
Beyond the solar system, Gliese 581 c is at the right distance from its sun for liquid water to exist on the planet's surface. Gliese 581 c (ˈgliːzə is a " Super-earth " Since it does not transit its sun, there is no way to know if there is any water there. HD 209458b may have water vapour in its atmosphere - this is currently being disputed. HD 209458 b, also unofficially named Osiris, is an Extrasolar planet that orbits the Solar twin Star HD 209458 in the constellation Gliese 436 b is believed to have 'hot ice'. Gliese 436 b (ˈgliːzə ( GJ 436 b) is a Neptune -sized Extrasolar planet orbiting the red dwarf star Gliese 436. Neither of these planets are cool enough for liquid water: but if water molecules exist there, they are likely to be found also on planets at a suitable temperature. 
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. Mesopotamian mythology is the collective name given to Sumerian Akkadian Assyrian and Babylonian mythologies from the land between the Tigris The existence of similarities among the deities and religious practices of the Indo-European (IE peoples allows glimpses of a common Proto-Indo-European Okeanos, "Ωκεανός" in Greek, reflects the ancient Greek observation that a strong current flowed off Gibraltar and their subsequent assumption that it was a great river. Ocean (Ὠκεανός was believed to be the world-ocean in Classical antiquity, which the ancient Romans and Greeks considered to be Greek mythology is the body of stories belonging to the ancient Greeks concerning their gods and Heroes the nature of the world and the origins and significance Gibraltar (dʒɨˈbrɒltər is a British overseas territory located near the southernmost tip of the Iberian Peninsula overlooking the Strait of Gibraltar (Compare also Samudra from Hindu mythology and Jörmungandr from Norse mythology). Samudra is a Sanskrit term for " Ocean " literally the "gathering together of waters" ( Saṃ - meaning "together" Hindu mythology is the large body of Mythology related to Hinduism, notably as contained in Sanskrit literature, such as the Sanskrit epics and Jörmungandr, alternately referred to as the Midgardsormr or World Serpent, is a Sea serpent of the Norse mythology, the middle child of the Norse mythology comprises the indigenous pre-Christian religion, beliefs and Legends of the Scandinavian peoples including those who settled on Iceland The world was imagined to be enclosed by a celestial ocean above the heavens, and an ocean of the underworld below (compare Rasā, Varuna). Several mythologies have the notion of a celestial ocean or river, enveloping the World both above the heavenly sphere and below the Underworld Rasa ( rásā sa रसा means "moisture humidity" in Vedic Sanskrit, and appears as the name of a western tributary of the Indus in the In Vedic religion, Varuna or Waruna ( Devanagari:वरुण IAST: varuṇa) is a god of the Sky, of Rain and