The
Pacific Ocean is the largest of the
Earth's
oceanic divisions.
Its name
is derived from the Latin name Tepre
Pacificum, "peaceful sea", bestowed upon it by the Portuguese
explorer Ferdinand
Magellan. It extends from the Arctic in the north to Antarctica
in the south, bounded by Asia
and Australia
in the west, and the Americas in the east. At169.2 million square
kilometres (65.3 million square miles) in area, this largest
division of the
World Ocean – and, in
turn, the
hydrosphere – covers about 46%
of the Earth's water surface and about 30% of its total surface.
The
equator subdivides it into the North
Pacific Ocean and South Pacific Ocean,
with two exceptions: the Galápagos
and Gilbert Islands,
while straddling the equator, are deemed wholly within the South
Pacific. The Mariana Trench
in the western North Pacific is the deepest point
in the Pacific and in the world, reaching a depth of .

The Pacific Ocean.
Overview
The 'Pacific ocean' encompasses aproximately a third of the
Earth's surface, having an area of 179.7
million square kilometres (69.4 million sq mi and 161 million cubic
mi) —significantly larger than Earth's entire landmass, with room
for another
Africa to spare.
Extending
approximately 15,500 kilometres (9,600 mi) from the
Bering
Sea
in the Arctic to the icy
margins of Antarctica
's Ross
Sea
in the south (although the Antarctic regions of the
Pacific are sometimes described as part of the circumpolar Southern Ocean
), the Pacific reaches its greatest east-west width
at about 5°N latitude, where it
stretches approximately 19,800 kilometres (12,300 mi)
from Indonesia
to the coast of Colombia
and Peru
– halfway
across the world, and more than five times the diameter of the
Moon. The western limit of the ocean is often
placed at the Strait of
Malacca
. The lowest known point on earth—the Mariana Trench
—lies 10,911 metres (35,797 ft) below sea
level. Its average depth is 4,280 metres
(14,000 ft).
The Pacific contains about 25,000
islands (more than the total number in the
rest of the world's oceans combined), the majority of which are
found south of the
equator. Including
partially submerged islands, the figure is substantially
higher.
The
Pacific Ocean is currently shrinking from plate tectonics, while the Atlantic Ocean
is increasing in size, by roughly an inch per year
(2–3 cm/yr) on 3 sides, roughly averaging 0.2 square miles
(0.5 km2) a year.
Along the
Pacific Ocean's irregular western margins lie many seas, the
largest of which are the Celebes Sea
, Coral
Sea
, East China
Sea
, Philippine
Sea
, Sea of
Japan
, South China
Sea
, Sulu
Sea
, Tasman
Sea
, and Yellow
Sea
. The Strait of Malacca
joins the Pacific and the Indian Oceans
on the west, and Drake Passage
and the Straits of Magellan
link the Pacific with the Atlantic Ocean
on the east. To the north, the Bering Strait
connects the Pacific with the Arctic Ocean
.
As the
Pacific straddles the ± 180°
meridian, the West Pacific (or western
Pacific, near Asia) is in the Eastern Hemisphere, while the East
Pacific (or eastern Pacific, near the Americas) is in
the Western
Hemisphere
.
For most
of Magellan's voyage from the Strait of Magellan
to the Philippines
, the explorer indeed found the ocean
peaceful. However, the Pacific is not always peaceful. Many
tropical storms batter the islands of the Pacific. The lands around
the Pacific rim are full of
volcanoes and
often affected by
earthquakes.
Tsunamis, caused by underwater earthquakes, have
devastated many islands and destroyed entire towns.
Water characteristics
Water temperatures in the Pacific vary from freezing in the
poleward areas to about near the equator.
Salinity also varies latitudinally. The water near
the equator is less salty than that found in the mid-latitudes
because of abundant equatorial precipitation throughout the year.
Poleward of the temperate latitudes salinity is also low, because
little evaporation of seawater takes place in these frigid
areas.
The
motion of Pacific waters is generally clockwise in the Northern
Hemisphere
(the North Pacific
gyre) and counter-clockwise in the Southern
Hemisphere
. The
North Equatorial Current, driven
westward along
latitude 15°N by
the
trade winds, turns north near the
Philippines to become the warm Japan or
Kuroshio Current.
Turning eastward at about
45°N,
the Kuroshio forks and some waters move northward as the
Aleutian Current, while the rest turn
southward to rejoin the North Equatorial Current. The Aleutian
Current branches as it approaches North America and forms the base
of a counter-clockwise circulation in the Bering Sea. Its southern
arm becomes the chilled slow, south-flowing California
Current.
The
South Equatorial Current,
flowing west along the equator, swings southward east of New Guinea
, turns east at about 50°S, and joins the main westerly
circulation of the Southern Pacific, which includes the
Earth-circling Antarctic
Circumpolar Current. As it approaches the Chilean
coast, the South Equatorial Current divides; one
branch flows around Cape
Horn
and the other turns north to form the Peru or
Humboldt Current.
Geology
The
andesite line is the most
significant regional distinction in the Pacific. It separates the
deeper,
mafic igneous
rock of the Central Pacific Basin from the partially submerged
continental areas of
felsic igneous rock on
its margins.
The andesite line follows the western edge
of the islands off California
and passes south of the Aleutian arc
, along the eastern edge of the Kamchatka
Peninsula
, the Kuril Islands
, Japan
, the
Mariana
Islands
, the Solomon Islands
, and New
Zealand
's North
Island
. The dissimilarity continues northeastward
along the western edge of the Andes Cordillera
along South America to Mexico
, returning
then to the islands off California. Indonesia
, the Philippines, Japan, New Guinea, and New
Zealand—all eastward extensions of the continental blocks of
Asia, Australia and
Zealandia—lie outside the
Andesite Line.
The pacific ocean takes up roughly one third of the earth's
surface, having an area of 179.7 million square kilometres. The
Pacific contains about 25,000 islands (more than the total number
in the rest of the world's oceans combined), the majority of which
are found south of the equator, Including partially submerged
islands. The pacific ocean was mapped by a man named Abraham
Ortelius, he called it Maris Pacifici because if you name it more
accurately it is named the Descriptio Maris Pacifici which is
interpreted as; Description of the Pacific Sea. The pacific ocean
has several long seamount chains (which are chains of mountains
submerging from the ocean seafloor) formed by hotspot volcanism.
“the ring of fire” is the worlds largest belt of explosive
volcanism. The Ring of Fire is named after the several hundred
active volcanoes that sit above the various subduction zones(which
is a geological process in which one edge of a crustal plate is
forced sideways and downward into the mantle below another
plate).
Within the closed loop of the Andesite Line are most of the deep
troughs, submerged volcanic mountains, and oceanic volcanic islands
that characterize the Pacific basin. Here basaltic lavas gently
flow out of rifts to build huge dome-shaped volcanic mountains
whose eroded summits form island arcs, chains, and clusters.
Outside the Andesite Line, volcanism is of the explosive type, and
the
Pacific Ring of Fire is the
world's foremost belt of explosive volcanism. The Ring of Fire is
named after the several hundred active volcanoes that sit above the
various subduction zones.
The Pacific Ocean is the only ocean which is almost totally bounded
by subduction zones. Only the Antarctic and Australian coasts have
no nearby subduction zones.
Seamount chains
The Pacific Ocean contains several long
seamount chains, formed by
hotspot volcanism.
These include the
Emperor
Seamounts
chain, the Louisville seamount chain, and the
Hawaiian Islands.
Landmasses

Right
The
largest landmass entirely within the Pacific Ocean is the island of New Guinea
— the second largest island in the world.
Almost
all of the smaller islands of the Pacific lie between 30°N and
30°S, extending from Southeast Asia
to Easter
Island
; the rest of the Pacific Basin is almost entirely
submerged. During the Last glacial period, New Guinea was part
of Australia so the largest landmass would have been Borneo
–Palawan
.
The great
triangle of Polynesia, connecting Hawaii
, Easter Island
, and New
Zealand
, encompasses the island arcs and clusters of the
Cook
Islands
, Marquesas Islands
, Samoa
, Society
, Tokelau
, Tonga
, Tuamotu
, Tuvalu
and the
Wallis and
Futuna
islands.
North of
the equator and west of the International Date Line
are the numerous small islands of Micronesia, including the Caroline
Islands
, the Marshall Islands
and the Mariana Islands
.
In the southwestern corner of the Pacific lie the islands of
Melanesia, dominated by New Guinea.
Other
important island groups of Melanesia include the Bismarck
Archipelago
, Fiji
, New Caledonia
, the Solomon Islands
and Vanuatu
.
Islands in the Pacific Ocean are of four basic types: continental
islands, high islands, coral reefs, and uplifted coral platforms.
Continental islands lie outside the Andesite line and include New Guinea, the
islands of New Zealand, and the Philippines
. These islands are structurally associated
with nearby continents. High islands are of volcanic origin, and
many contain active volcanoes.
Among these are Bougainville
, Hawaii, and the Solomon Islands.
The third and fourth types of islands are both the result of
coralline island building. Coral reefs are low-lying structures
that have built up on basaltic lava flows under the ocean's
surface.
One of the most dramatic is the Great
Barrier Reef
off northeastern Australia. A second island type formed of
coral is the uplifted coral platform, which is usually slightly
larger than the low coral islands.
Examples include Banaba
(formerly
Ocean Island) and Makatea
in the Tuamotu group of French Polynesia
.
History and economy
Important
human migrations occurred in the Pacific in prehistoric times, most
notably those of the Polynesians from the
Asian edge of the ocean to Tahiti
and then
to Hawaii
, New Zealand
, and Easter Island
.
The ocean was sighted by Europeans early in the 16th century, first
by the Spanish explorer
Vasco Núñez de Balboa who
crossed the
Isthmus of Panama in
1513, and then by the Portuguese explorer
Ferdinand Magellan, who sailed the
Pacific during his circumnavigation from 1519 to 1522.
In 1564, conquistadors crossed the ocean from Mexico led
by Miguel López de
Legazpi who sailed to the Philippines
and Mariana Islands
. For the remainder of the 16th century,
Spanish influence was paramount, with ships sailing from Spain
to the
Philippines, New
Guinea
, and the Solomon Islands
.
During
the 17th century, the Dutch, sailing around southern Africa,
dominated discovery and trade; Abel Janszoon
Tasman discovered Tasmania
and New
Zealand
in 1642. The 18th century marked a burst of
exploration by the Russians in Alaska
and the
Aleutian
Islands
, the French in Polynesia,
and the British in the three voyages of James
Cook to the South Pacific and Australia, Hawaii
, and the
North American Pacific
Northwest.
Growing
imperialism during the 19th century
resulted in the occupation of much of Oceania by European powers,
and later, the United
States
and Japan
.
Significant contributions to oceanographic knowledge were made by
the voyages of
HMS Beagle in the
1830s, with
Charles Darwin aboard;
HMS Challenger during the
1870s; the
USS
Tuscarora (1873–76); and the German
Gazelle
(1874–76).
Although the United States gained control of
the Philippines
from Spain
in 1898,
Japan controlled most of the western Pacific by 1914 and occupied
many other islands during World War
II. However, by the end of that war, Japan was defeated
and the
U.S. Pacific Fleet was the virtual master of
the ocean. Since the end of World War II, many former colonies in
the Pacific have become independent
state.
The exploitation of the Pacific's mineral wealth is hampered by the
ocean's great depths.
In shallow waters of the continental shelves
off the coasts of Australia and New Zealand, petroleum and natural
gas are extracted, and pearls are
harvested along the coasts of Australia,
Japan
, Papua New
Guinea
, Nicaragua
, Panama
, and the
Philippines
, although in sharply declining volume in some
cases. The Pacific's greatest asset is its fish. The
shoreline waters of the continents and the more temperate islands
yield
herring,
salmon,
sardines,
snapper,
swordfish, and
tuna, as well
as
shellfish.
Environmental issues
Marine pollution is a generic term for the harmful entry into the
ocean of chemicals or particles. The biggest culprits are people
who use the rivers for disposing of their waste. The rivers then
empty into the Ocean, and with it the many chemicals used as
fertilizers in agriculture. The excess of
oxygen depleting chemicals in the water leads to
hypoxia and the creation of a
dead zone.
Marine debris, also known as marine
litter, is a term used to describe human-created waste that has
found itself floating in a lake, sea, ocean or waterway. Oceanic
debris tends to accumulate at the centre of gyres and coastlines,
frequently washing aground where it is known as beach litter.
Bordering countries and territories
Major ports and harbours
- Acapulco
, Guerrero
, Mexico
- Anchorage, Alaska
, United
States
- Antofagasta
, Chile
- Arica
, Chile
- Auckland
, New
Zealand
- Bacolod City
, Philippines
- Bangkok
, Thailand
- Batangas
, Philippines
- Bluff
, New
Zealand
- Brisbane,
Queensland
, Australia
- Buenaventura, Colombia

- Busan
, South Korea
- Cabo San Lucas
, Baja California Sur
, Mexico
- Cagayan de Oro City
, Philippines
- Callao
, Peru
- Cebu
City
, Philippines
- Chongjin
, North
Korea
- Dalian, People's
Republic of China

- Danang
, Vietnam
- Davao
City
, Philippines
- Ensenada, Baja California
, Mexico
- Esmeraldas
, Ecuador
- Guayaquil
, Ecuador
- Haiphong
, Vietnam
- Hong
Kong
, People's Republic of China
- Honolulu, Hawaii
, United
States
- Incheon
, South
Korea
- Iloilo
, Philippines
- Iquique
, Chile
- Jayapura
, Indonesia
- Kaohsiung
, Republic of China 
- Kitimat, British Columbia
, Canada
- Keelung
, Republic of China
(Taiwan)
- Kobe, Japan

- Kuala Terengganu
, Malaysia
- Laem Chabang
, Thailand
- Lyttelton, New
Zealand
- Long Beach, California
, United States
- Los Angeles, California
, United States
- Manta
,
Ecuador
- Manzanillo, Colima
, Mexico
- Mazatlán
, Sinaloa
, Mexico
- Melbourne, Victoria
, Australia
- Manila
, Philippines
- Nampho
, North
Korea
- Newcastle, New South Wales
, Australia
- Oakland, California
, United States
- Panama City
, Panama
- Portland, Oregon
, United States
- Portoviejo
, Ecuador
- Prince Rupert, British
Columbia
, Canada
- Puerto Chacabuco
, Chile
- Puerto Montt
, Chile
- Puerto Vallarta
, Jalisco
, Mexico
- Pyeongtaek
, South
Korea
- Qingdao
, People's Republic of China
- Saigon
, Vietnam
- San Antonio
, Chile
- San
Diego, California
, United
States
- San Francisco, California
, United States
- Seattle, Washington
, United States
- Shanghai, People's
Republic of China

- Shenzhen
, People's Republic of China
- Singapore

- Songkhla
, Thailand
- Sydney, New South Wales
, Australia
- Tacoma, Washington
, United States
- Taichung
, Republic of China (Taiwan)
- Talcahuano
, Chile
- Tauranga
, New
Zealand
- Tianjin
, People's Republic of China
- Tijuana
, Baja
California
, Mexico
- Tokyo
, Japan
- Tumaco
, Colombia
- Valparaíso
, Chile
- Vancouver, British Columbia
, Canada
- Victoria, British Columbia
, Canada
- Vladivostok
, Russia
- Wollongong, New South Wales
, Australia
- Xiamen
, People's Republic of China
- Yantai, People's
Republic of China

- Yokohama, Japan

- Zamboanga
, Philippines
See also
References
Further reading
- Based on public domain text from US Naval
Oceanographer
External links