# Newbi By [Author](https://paragraph.com/@nolunt) · 2022-06-05 --- about ocean The **ocean** (also the [**sea**](https://en.wikipedia.org/wiki/Sea) or the **world ocean**) is the body of [salt water](https://en.wikipedia.org/wiki/Saline_water) that covers approximately 70.8% of the surface of [Earth](https://en.wikipedia.org/wiki/Earth) and contains 97% of [Earth's water](https://en.wikipedia.org/wiki/Water_distribution_on_Earth).[\[1\]](https://en.wikipedia.org/wiki/Ocean#cite_note-1) In other words, an ocean is "any of the large bodies of water into which the great ocean is divided".[\[2\]](https://en.wikipedia.org/wiki/Ocean#cite_note-:0-2) Separate names are used to identify five different areas of the ocean: [Pacific](https://en.wikipedia.org/wiki/Pacific_Ocean) (the largest), [Atlantic](https://en.wikipedia.org/wiki/Atlantic_Ocean), [Indian](https://en.wikipedia.org/wiki/Indian_Ocean), [Southern](https://en.wikipedia.org/wiki/Southern_Ocean) (Antarctic), and [Arctic](https://en.wikipedia.org/wiki/Arctic_Ocean) (the smallest).[\[3\]](https://en.wikipedia.org/wiki/Ocean#cite_note-oed.130201-3)[\[4\]](https://en.wikipedia.org/wiki/Ocean#cite_note-mw.ocean-4) [Seawater](https://en.wikipedia.org/wiki/Seawater) covers approximately 361,000,000 km2 (139,000,000 sq mi) of the planet. The ocean is the principal component of Earth's [hydrosphere](https://en.wikipedia.org/wiki/Hydrosphere), and therefore integral to [life](https://en.wikipedia.org/wiki/Life) on Earth. Acting as a huge [heat reservoir](https://en.wikipedia.org/wiki/Ocean_heat_content), the ocean influences [climate](https://en.wikipedia.org/wiki/Climate) and [weather](https://en.wikipedia.org/wiki/Weather) patterns, the [carbon cycle](https://en.wikipedia.org/wiki/Carbon_cycle), and the [water cycle](https://en.wikipedia.org/wiki/Water_cycle). [Oceanographers](https://en.wikipedia.org/wiki/Oceanography) divide the ocean into different vertical and horizontal zones based on physical and biological conditions. The [pelagic zone](https://en.wikipedia.org/wiki/Pelagic_zone) consists of the [water column](https://en.wikipedia.org/wiki/Water_column) from surface to ocean floor throughout the open ocean. The water column is further categorized in other zones depending on depth and on how much light is present. The [photic zone](https://en.wikipedia.org/wiki/Photic_zone) includes water from the surface to a depth of 1% of the surface light (about 200 m in the open ocean), where [photosynthesis](https://en.wikipedia.org/wiki/Photosynthesis) can occur. This makes the photic zone the most [biodiverse](https://en.wikipedia.org/wiki/Biodiverse). Photosynthesis by plants and microscopic [algae](https://en.wikipedia.org/wiki/Algae) (free floating [phytoplankton](https://en.wikipedia.org/wiki/Phytoplankton)) creates organic matter using light, water, carbon dioxide, and nutrients. Ocean photosynthesis creates 50% of the oxygen in earth's atmosphere.[\[5\]](https://en.wikipedia.org/wiki/Ocean#cite_note-5) This upper sunlit zone is the origin of the food supply which sustains most of the ocean [ecosystem](https://en.wikipedia.org/wiki/Ecosystem). Light only penetrates to a depth of a few hundred meters; the remaining ocean below is cold and dark. The [continental shelf](https://en.wikipedia.org/wiki/Continental_shelf) where the ocean approaches dry land is more shallow, with a depth of a few hundred meters or less. Human activity has a greater impact on the [continental shelf](https://en.wikipedia.org/wiki/Continental_shelf).   Ocean temperatures depend on the amount of solar radiation reaching the ocean surface. In the tropics, surface temperatures can rise to over 30 °C (86 °F). Near the poles where [sea ice](https://en.wikipedia.org/wiki/Sea_ice) forms, the temperature in equilibrium is about −2 °C (28 °F). Deep seawater temperature is between −2 °C (28 °F) and 5 °C (41 °F) in all parts of the ocean.[\[6\]](https://en.wikipedia.org/wiki/Ocean#cite_note-:7-6) Water continuously circulates in the oceans creating [ocean currents](https://en.wikipedia.org/wiki/Ocean_current). These directed movements of seawater are generated by forces acting upon the water, including temperature differences, [atmospheric circulation](https://en.wikipedia.org/wiki/Atmospheric_circulation) (wind), the [Coriolis effect](https://en.wikipedia.org/wiki/Coriolis_effect) and differences in [salinity](https://en.wikipedia.org/wiki/Salinity).[\[7\]](https://en.wikipedia.org/wiki/Ocean#cite_note-:8-7) Tidal currents originate from [tides](https://en.wikipedia.org/wiki/Tide), while surface currents are caused by wind and waves. Major ocean currents include the [Gulf Stream](https://en.wikipedia.org/wiki/Gulf_Stream), [Kuroshio current](https://en.wikipedia.org/wiki/Kuroshio_Current), [Agulhas current](https://en.wikipedia.org/wiki/Agulhas_Current) and [Antarctic Circumpolar Current](https://en.wikipedia.org/wiki/Antarctic_Circumpolar_Current). Collectively, currents move enormous amounts of water and heat around the globe. This circulation significantly impacts global climate and the uptake and redistribution of pollutants such as [carbon dioxide](https://en.wikipedia.org/wiki/Carbon_dioxide) by moving these contaminants from the surface into the deep ocean. Ocean water contains large quantities of dissolved gases, including [oxygen](https://en.wikipedia.org/wiki/Oxygen), [carbon dioxide](https://en.wikipedia.org/wiki/Carbon_dioxide) and [nitrogen](https://en.wikipedia.org/wiki/Nitrogen). This [gas exchange](https://en.wikipedia.org/wiki/Gas_exchange) takes place at the ocean surface and solubility depends on the temperature and salinity of the water.[\[8\]](https://en.wikipedia.org/wiki/Ocean#cite_note-:9-8) The increasing concentration of [carbon dioxide in the atmosphere](https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere) due to [fossil fuel](https://en.wikipedia.org/wiki/Fossil_fuel) combustion leads to higher concentrations in ocean water, resulting in [ocean acidification](https://en.wikipedia.org/wiki/Ocean_acidification).[\[9\]](https://en.wikipedia.org/wiki/Ocean#cite_note-:10-9) The ocean provides society with important [environmental services](https://en.wikipedia.org/wiki/Ecosystem_service), including climate regulation. It also offers a means of [trade](https://en.wikipedia.org/wiki/Trade) and transport and access to food and other [resources](https://en.wikipedia.org/wiki/Resource). Known to be the [habitat](https://en.wikipedia.org/wiki/Habitat) of over 230,000 [species](https://en.wikipedia.org/wiki/Species), it may contain far more – perhaps over two million species.[\[10\]](https://en.wikipedia.org/wiki/Ocean#cite_note-la.2009-10) However, the ocean is subject to numerous [environmental](https://en.wikipedia.org/wiki/Environmental_issues) threats, including [marine pollution](https://en.wikipedia.org/wiki/Ocean#Marine_pollution), [overfishing](https://en.wikipedia.org/wiki/Ocean#Overfishing), [ocean acidification](https://en.wikipedia.org/wiki/Ocean#Ocean_acidification) and other [effects of climate change](https://en.wikipedia.org/wiki/Effects_of_climate_change_on_oceans). The continental shelf and [coastal waters](https://en.wikipedia.org/wiki/Coast) that are most influenced by human activity are especially copy from WIKI --- *Originally published on [Author](https://paragraph.com/@nolunt/newbi)*