Ocean

These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans.

The Pacific Ocean is the largest and deepest of Earth's oceanic divisions.

These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans.

The Atlantic Ocean is the second largest of the world's oceans, with an area of about 106,460,000 km2.

These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans.

The Indian Ocean is the third-largest of the world's oceanic divisions, covering 70560000 km2 or 19.8% of the water on the Earth's surface.

These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans.

The Arctic Ocean is the smallest and shallowest of the world's five major oceans.

On Earth, an ocean is one of the major conventional divisions of the World Ocean.

About 71% of Earth's surface is covered with water, mostly by oceans.

On Earth, an ocean is one of the major conventional divisions of the World Ocean.

The World Ocean or Global Ocean (colloquially the sea or the ocean) is the interconnected system of Earth's oceanic waters, and comprises the bulk of the hydrosphere, covering 361132000 km2 (70.8%) of Earth's surface, with a total volume of roughly 1,332,000,000 km3.

An ocean is a body of water that composes much of a planet's hydrosphere.

Water covers 71% of the Earth's surface, mostly in seas and oceans.

The ocean contains 97% of Earth's water, and oceanographers have stated that less than 5% of the World Ocean has been explored.

Oceanography (compound of the Greek words ὠκεανός meaning "ocean" and γράφω meaning "write"), also known as oceanology, is the study of the physical and biological aspects of the ocean.

Strictly speaking, a sea is a body of water (generally a division of the world ocean) partly or fully enclosed by land, though "the sea" refers also to the oceans. The word ocean comes from the figure in classical antiquity, Oceanus ( Ōkeanós, ), the elder of the Titans in classical Greek mythology, believed by the ancient Greeks and Romans to be the divine personification of the sea, an enormous river encircling the world.

Salinity varies widely, being lower near the surface and the mouths of large rivers and higher in the depths of the ocean; however, the relative proportions of dissolved salts varies little across the oceans.

The origin of Earth's oceans is unknown; oceans are thought to have formed in the Hadean eon and may have been the cause for the emergence of life.

Earth is unique among the rocky planets in the Solar System in that it is the only planet with oceans of liquid water on its surface.

An ocean is a body of water that composes much of a planet's hydrosphere. The total mass of the hydrosphere is about 1.4 quintillion tonnes (1.4 long tons or 1.5 short tons), which is about 0.023% of Earth's total mass. Less than 3% is freshwater; the rest is saltwater, almost all of which is in the ocean.

This includes water in liquid and frozen forms in groundwater, oceans, lakes and streams.

The word ocean comes from the figure in classical antiquity, Oceanus ( Ōkeanós, ), the elder of the Titans in classical Greek mythology, believed by the ancient Greeks and Romans to be the divine personification of the sea, an enormous river encircling the world.

A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river.

Oceans are fringed by smaller, adjoining bodies of water such as seas, gulfs, bays, bights, and straits.

Oceans are fringed by smaller, adjoining bodies of water such as seas, gulfs, bays, bights, and straits.

A gulf in geography is a large bay that is an arm of an ocean or sea.

Oceans are fringed by smaller, adjoining bodies of water such as seas, gulfs, bays, bights, and straits.

A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay.

The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, and other criteria.

Earth's major landmasses all have coasts on a single, continuous World Ocean, which is divided into a number of principal oceanic components by the continents and various geographic criteria.

The total mass of the hydrosphere is about 1.4 quintillion tonnes (1.4 long tons or 1.5 short tons), which is about 0.023% of Earth's total mass. Less than 3% is freshwater; the rest is saltwater, almost all of which is in the ocean.

Seawater, or salt water, is water from a sea or ocean.

The word ocean comes from the figure in classical antiquity, Oceanus ( Ōkeanós, ), the elder of the Titans in classical Greek mythology, believed by the ancient Greeks and Romans to be the divine personification of the sea, an enormous river encircling the world.

According to Homer, Oceanus was the ocean-stream at the margin of the habitable world (οἰκουμένη, oikouménē), the father of everything, limiting it from the underworld and flowing around the Elysium.

Mariners and other seafarers have reported that the ocean often emits a visible glow which extends for miles at night.

Milky seas, also called mareel, is a luminous phenomenon in the ocean in which large areas of seawater (up to 6000 mi2) appear to glow brightly enough at night to be seen by satellites orbiting Earth.

The mid-ocean ridges of the world are connected and form a single global mid-oceanic ridge system that is part of every ocean and the longest mountain range in the world.

The mid-ocean ridges of the world are connected and form the Ocean Ridge, a single global mid-oceanic ridge system that is part of every ocean, making it the longest mountain range in the world.

The benthic zones are aphotic and correspond to the three deepest zones of the deep-sea.

The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers.

Its lowermost boundary is at a thermocline of 12 C, which, in the tropics generally lies at 700 - 1000 m. Next is the bathypelagic lying between 10 and 4 C, typically between 700 - 1000 m and 2000 - 4000 m, lying along the top of the abyssal plain is the abyssopelagic, whose lower boundary lies at about 6000 m. The last zone includes the deep oceanic trench, and is known as the hadalpelagic.

The hadal zone (named after the realm of Hades, the underworld in Greek mythology), also known as the hadopelagic zone, is the deepest region of the ocean lying within oceanic trenches.

Because plants require photosynthesis, life found deeper than the photic zone must either rely on material sinking from above (see marine snow) or find another energy source.

Export production is the amount of organic matter produced in the ocean by primary production that is not recycled (remineralised) before it sinks into the aphotic zone.

The benthic zones are aphotic and correspond to the three deepest zones of the deep-sea.

The deep sea or deep layer is the lowest layer in the ocean, existing below the thermocline and above the seabed, at a depth of 1000 fathoms (1800 m) or more.

In 1960, the Trieste successfully reached the bottom of the trench, manned by a crew of two men.

Trieste is a Swiss-designed, Italian-built deep-diving research bathyscaphe, which with its crew of two reached a record maximum depth of about 10911 m, in the deepest known part of the Earth's oceans, the Challenger Deep, in the Mariana Trench near Guam in the Pacific.