Editing Indian Ocean (section)

==Geography==
{{multiple image
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| image1            = Indian Ocean surface.jpg
| caption1          = The ocean-floor of the Indian Ocean is divided by spreading ridges and crisscrossed by aseismic structures
| image2            = Blue Marble Eastern Hemisphere.jpg
| caption2          = A composite satellite image centred on the Indian Ocean
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===Extent and data===
The [[Borders of the oceans#Indian Ocean|borders of the Indian Ocean]], as delineated by the [[International Hydrographic Organization]] in 1953, included the [[Southern Ocean]] but not the marginal seas along the northern rim.<ref>{{Harvnb|IHO 1953}}</ref> In 2002 the IHO delimited the Southern Ocean separately, which removed waters south of 60°S from the Indian Ocean but included the northern marginal seas.<ref name="IHO-2002">{{Harvnb|IHO 2002}}</ref> [[Meridional]]ly, the Indian Ocean is delimited from the Atlantic Ocean by the [[20th meridian east|20° east meridian]], running south from [[Cape Agulhas]], South Africa, and from the Pacific Ocean by the meridian of 146°49'E, running south from [[South East Cape]] on the island of [[Tasmania]] in Australia. The northernmost extent of the Indian Ocean (including marginal seas) is approximately [[30th parallel north|30°N]] in the [[Persian Gulf]].<ref name="IHO-2002" /><!-- Fig. 1, p. 5-2 -->

The Indian Ocean covers {{Convert|70560000|km2|abbr=on}}, including the [[Red Sea]] and the Persian Gulf but excluding the Southern Ocean, or 19.5% of the world's oceans. Its volume is {{Convert|264000000|km3|abbr=on}} or 19.8% of the world's oceans' volume; it has an average depth of {{Convert|3741|m|abbr=on}} and a maximum depth of {{Convert|7290|m|abbr=on}}.<ref name="NOAA-volume" />

All of the Indian Ocean is in the [[Eastern Hemisphere]]. The centre of the Eastern Hemisphere, the [[90th meridian east]], passes through the [[Ninety East Ridge]].

Within these waters are a number of islands. These include those controlled by surrounding countries, and independent island states and territories. Of the non-coastal islands, there are two broad clusters: one around Madagascar, and one south of India. A few other oceanic islands are scattered elsewhere.<ref name="Bergin2019">{{cite journal|author1=Anthony Bergin|author2=David Brewster|author3=Aakriti Bachhawat|title=Ocean Horizons: Strengthening Maritime Security in Indo-Pacific Island States|journal=Indian Ocean Island States|date=1 December 2019|pages=29–39|url=https://www.jstor.org/stable/resrep23122.6}}</ref>{{rp|29–30}}

===Coasts and shelves===
In contrast to the Atlantic and Pacific, the Indian Ocean is enclosed by major landmasses and an archipelago on three sides and does not stretch from pole to pole, and can be likened to an embayed ocean. It is centered on the Indian Peninsula. Although this subcontinent has played a significant role in its history, the Indian Ocean has foremostly been a cosmopolitan stage, interlinking diverse regions by innovations, trade, and religion since early in human history.<ref name="Prange-2008-p1382">{{Harvnb|Prange|2008|loc=Fluid Borders: Encompassing the Ocean, pp. 1382–1385}}</ref>

The [[active margin]]s of the Indian Ocean have an average width (horizontal distance from land to shelf break<ref>{{Cite web|date=4 March 2011|title=Continental Shelf|url=https://education.nationalgeographic.org/resource/continental-shelf/|access-date=5 October 2021|publisher=National Geographic Society|language=en|archive-date=5 October 2021|archive-url=https://web.archive.org/web/20211005141557/https://www.nationalgeographic.org/encyclopedia/continental-shelf/|url-status=live}}</ref>) of {{Convert|19|+/-|0.61|km|abbr=on}} with a maximum width of {{Convert|175|km|abbr=on}}. The [[passive margin]]s have an average width of {{Convert|47.6|+/-|0.8|km|abbr=on}}.<ref>{{Harvnb|Harris|Macmillan-Lawler|Rupp|Baker|2014|loc=Table 2, p. 11}}</ref>
The average width of the [[Continental slope|slopes]] (horizontal distance from shelf break to foot of slope) of the continental shelves are {{Convert|50.4|-|52.4|km|abbr=on}} for active and passive margins respectively, with a maximum width of {{Convert|205.3|-|255.2|km|abbr=on}}.<ref>{{Harvnb|Harris|Macmillan-Lawler|Rupp|Baker|2014|loc=Table 3, p. 11}}</ref>

In correspondence of the [[Shelf break]], also known as Hinge zone, the [[Bouguer gravity]] ranges from 0 to 30 [[Gal (unit)|mGals]] that is unusual for a continental region of around 16&nbsp;km thick sediments. It has been hypothesized that the "Hinge zone may represent the relict of continental and proto-oceanic crustal boundary formed during the rifting of India from [[Antarctica#Geography|Antarctica]]."<ref name="1365-246X_208_3">{{cite journal|last1=Damodara|first1=N.|last2=Rao|first2=V. Vijaya|last3=Sain|first3=Kalachand|last4=Prasad|first4=A.S.S.S.R.S.|last5=Murty|first5=A.S.N.|title=Basement configuration of the West Bengal sedimentary basin, India as revealed by seismic refraction tomography: its tectonic implications|journal=Geophysical Journal International|date=March 2017|volume=208|issue=3|pages=1490–1507|doi=10.1093/gji/ggw461|doi-access=free}}</ref>

Australia, Indonesia, and India are the three countries with the longest shorelines and [[exclusive economic zone]]s. The continental shelf makes up 15% of the Indian Ocean.
More than two billion people live in countries bordering the Indian Ocean, compared to 1.7 billion for the Atlantic and 2.7 billion for the Pacific (some countries border more than one ocean).<ref name="KeeIrv-2005" />

====Rivers====
The Indian Ocean [[drainage basin]] covers {{Convert|21100000|km2|abbr=on}}, virtually identical to that of the Pacific Ocean and half that of the Atlantic basin, or 30% of its ocean surface (compared to 15% for the Pacific). The Indian Ocean drainage basin is divided into roughly 800 individual basins, half that of the Pacific, of which 50% are located in Asia, 30% in Africa, and 20% in Australasia. The rivers of the Indian Ocean are shorter on average ({{Convert|740|km|abbr=on}}) than those of the other major oceans. The largest rivers are ([[Strahler number|order 5]]) the [[Zambezi]], [[Ganges River|Ganges]]-[[Brahmaputra]], [[Indus River|Indus]], [[Jubba River|Jubba]], and [[Murray River|Murray]] rivers and (order 4) the [[Shatt al-Arab]], [[Wadi Ad Dawasir]] (a dried-out river system on the Arabian Peninsula) and [[Limpopo River|Limpopo]] rivers.<ref>{{Harvnb|Vörösmarty|Fekete|Meybeck|Lammers|2000|loc=Drainage basin area of each ocean, pp. 609–616; Table 5, p 614; Reconciling Continental and Oceanic Perspectives, pp. 616–617}}</ref> After the breakup of East [[Gondwana]] and the formation of the Himalayas, the Ganges-Brahmaputra rivers flow into the world's largest delta known as the [[Bengal delta]] or [[Sunderbans]].<ref name="1365-246X_208_3" />

===Marginal seas===
[[Marginal seas]], gulfs, bays and straits of the Indian Ocean include:<ref name="IHO-2002" />

Along the east coast of Africa, the [[Mozambique Channel]] separates [[Madagascar]] from mainland Africa, while the [[Sea of Zanj]] is located north of Madagascar.

On the northern coast of the [[Arabian Sea]], [[Gulf of Aden]] is connected to the [[Red Sea]] by the strait of [[Bab-el-Mandeb]]. In the Gulf of Aden, the [[Gulf of Tadjoura]] is located in Djibouti and the [[Guardafui Channel]] separates Socotra island from the Horn of Africa. The northern end of the Red Sea terminates in the [[Gulf of Aqaba]] and [[Gulf of Suez]]. The Indian Ocean is artificially connected to the [[Mediterranean Sea]] without ship lock through the [[Suez Canal]], which is accessible via the Red Sea. The Arabian Sea is connected to the [[Persian Gulf]] by the [[Gulf of Oman]] and the [[Strait of Hormuz]]. In the Persian Gulf, the [[Gulf of Bahrain]] separates Qatar from the Arabic Peninsula.

Along the west coast of India, the [[Gulf of Kutch]] and [[Gulf of Khambat]] are located in Gujarat in the northern end while the [[Laccadive Sea]] separates the Maldives from the southern tip of India. The [[Bay of Bengal]] is off the east coast of India. The [[Gulf of Mannar]] and the [[Palk Strait]] separate Sri Lanka from India, while [[Adam's Bridge]] separates the two. The [[Andaman Sea]] is located between the Bay of Bengal and the Andaman Islands.

In Indonesia, the so-called [[Geology of Indonesia#Indonesian Seaway|Indonesian Seaway]] is composed of the [[Malacca Strait|Malacca]], [[Sunda Strait|Sunda]] and [[Torres Strait]]s.
The [[Gulf of Carpentaria]] is located on the Australian north coast while the [[Great Australian Bight]] constitutes a large part of its southern coast.<ref>{{Cite web|url=https://www.livescience.com/29533-the-worlds-biggest-oceans-and-seas.html|title=The World's Biggest Oceans and Seas|website=[[Live Science]]|date=4 June 2010|access-date=9 September 2020|archive-date=15 September 2020|archive-url=https://web.archive.org/web/20200915222930/https://www.livescience.com/29533-the-worlds-biggest-oceans-and-seas.html|url-status=live}}</ref><ref>{{cite web|url=https://www.worldatlas.com/|title=World Map / World Atlas / Atlas of the World Including Geography Facts and Flags – WorldAtlas.com|access-date=28 April 2019|archive-date=27 April 2019|archive-url=https://web.archive.org/web/20190427214956/https://www.worldatlas.com/|url-status=live}}</ref><ref>{{cite web|url=http://listofseas.com/|title=List of seas|access-date=9 September 2020|archive-date=8 November 2020|archive-url=https://web.archive.org/web/20201108163716/http://listofseas.com/|url-status=live}}</ref>

{{div col|colwidth=24em}}
# [[Arabian Sea]] – 3.862 million km<sup>2</sup>
# [[Bay of Bengal]] – 2.172 million km<sup>2</sup>
# [[Andaman Sea]] – 797,700&nbsp;km<sup>2</sup>
# [[Laccadive Sea]] – 786,000&nbsp;km<sup>2</sup>
# [[Mozambique Channel]] – 700,000&nbsp;km<sup>2</sup>
# [[Timor Sea]] – 610,000&nbsp;km<sup>2</sup>
# [[Red Sea]] – 438,000&nbsp;km<sup>2</sup>
# [[Gulf of Aden]] – 410,000&nbsp;km<sup>2</sup>
# [[Persian Gulf]] – 251,000&nbsp;km<sup>2</sup>
# [[Flores Sea]] – 240,000&nbsp;km<sup>2</sup>
# [[Molucca Sea]] – 200,000&nbsp;km<sup>2</sup>
# [[Gulf of Oman]] – 181,000&nbsp;km<sup>2</sup>
# [[Great Australian Bight]] – 45,926&nbsp;km<sup>2</sup>
# [[Gulf of Aqaba]] – 239&nbsp;km<sup>2</sup>
# [[Gulf of Khambhat]]
# [[Gulf of Kutch]]
# [[Gulf of Suez]]
# [[Dubai Canal]]
# [[Strait of Hormuz]]
{{div col end}}