地球表面被陆地分隔为彼此相通的广大水域称为海洋，其总面积约为3．6亿平方公里，约占地球表面积的71%。因为海洋面积远远大于陆地面积，故有人将地球称为“水球”。 海洋中含有十三亿五千多万立方千米的水，约占地球上总水量的97%。全球海洋一般被分为数个大洋和面积较小的海。四个主要的大洋为太平洋、大西洋和印度洋、北冰洋（有科学家又加上第五大洋，即南极洲附近的海域），大部分以陆地和海底地形线为界。海洋是地球上决定气候发展的主要因素之一。海洋本身是地球表面最大的储热体。海流是地球表面最大的热能传送带。海洋与空气之间的气体交换（其中最主要的有水汽、二氧化碳和甲烷）对气候的变化和发展有极大的影响。那么，海洋用英语怎么说呢？
[图片0]
What is ocean
什么是海洋
An ocean (from Greek, “okeanos” Oceanus) is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth’s surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.
More than half of this area is over 3,000 metres (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (‰) (%), and nearly all seawater has a salinity in the range of 30 to 38 ‰. Scientists estimate that 230,000 marine species are currently known, but the total could be up to 10 times that number.
Though generally described as several “separate” oceans, these waters comprise one global, interconnected body of salt water sometimes referred to as the World Ocean or global ocean. This concept of a continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography.
The major oceanic divisions are defined in part by the continents, various archipelagos, and other criteria. These divisions are (in descending order of size):
Pacific Ocean, which separates Asia and Australia from the Americas.
Atlantic Ocean, which separates the Americas from Eurasia and AfricaIndian Ocean, which washes upon southern Asia and separates Africa and AustraliaSouthern Ocean, sometimes considered an extension of the Pacific, Atlantic and Indian Oceans, which encircles Antarctica.
Arctic Ocean, sometimes considered a sea of the Atlantic, which covers much of the Arctic and washes upon northern North America and Eurasia.
The Pacific and Atlantic may be further subdivided by the equator into northern and southern portions. Smaller regions of the oceans are called seas, gulfs, bays, straits and other names.
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. Continental crust is thicker but less dense. From this perspective, the earth has three oceans: the World Ocean, the Caspian Sea, and Black Sea. The latter two were formed by the collision of Cimmeria with Laurasia. The Mediterranean Sea is at times a discrete ocean, because tectonic plate movement has repeatedly broken its connection to the World Ocean through the Strait of Gibraltar. The Black Sea is connected to the Mediterranean through the Bosporus, 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.
海洋灾害（marine hazards）主要指风暴潮（storm tide）灾害、巨浪（billow）灾害，海冰（sea ice）灾害、海雾(sea fog)灾害、大风灾害及地震海啸(earthquake and tsunami)灾害等突发性的自然灾害(natural calamities)。
引发海洋灾害的原因主要有大气的强烈扰动，如热带气旋(tropical cyclone)、温带气旋(extra tropical cyclone)等；海洋水体本身的扰动或状态骤变；海底地震（submarine earthquake）、火山爆发（volcanic explosion）及其伴生之海底滑坡（submarine landslide）、地裂缝（ground fissure）等。 海洋自然灾害不仅威胁海上及海岸，有些还危及自岸向陆广大纵深地区的城乡经济和人民生命财产的安全。世界上经济发达的海洋国家以及有关国际组织，都很重视海洋灾害的预警和防御。海洋灾害（现象）发生、发展、移行和消失的监视监测，是预警和防御体系最重要和最基本的内容。全球范围的海洋灾害监视监测是通过海洋监测（marine monitoring）或观测网实现的。