# River island

A river island is any exposed landmass surrounded by river water. Properly defined, it excludes shoals between seasonally varying flows and may exclude semi-coastal islands in river deltas such as Marajó.
These islands result from changes in the course of a river. Such changes may be caused by interactions with a tributary, or by the opposing fluvial actions of deposition and/or erosion that form a natural cut and meander. Nascent vegetation-free shoals and mudflats may dissipate and shift or build up into such islands through deposition; the process may be assisted through artificial reinforcement or natural factors, such as reeds, palms, evergreen trees or willows, that act as obstacles or erosion barriers, so that water flows around them. Islands may be small or large, covering many square kilometers, examples of which are given below.

## Regional nomenclature

The term "towhead" implies an islet (small island) or shoal within a river (most often the Mississippi River) having a grouping or thicket of trees, and is often used in the Midwestern United States. Many rivers, if wide enough, can house considerably large islands. The term "towhead" was popularised by Mark Twain's Adventures of Huckleberry Finn.
In England, a river island in the Thames is referred to as an "ait" (or "eyot").

## Largest and smallest

Majuli (a non-coastal landmass between two banks of a river), located in the Brahmaputra River in Assam, India, is recognised by Guinness World Records as the world's largest inhabited riverine island, at 880 square kilometres (340 sq mi).
The Encyclopædia Britannica cites another large non-coastal landmass, Bananal Island (an island that divides the Araguaia River into two branches over a 320 km (200-mile) length of water), located in Tocantins, central Brazil, to be the world's largest river island instead, at 19,162 square kilometres (7,398 sq mi).
However, Bananal Island is not considered a riverine island by some geologists, as they consider the Araguaia River to form two distributaries, and Bananal Island to be the landmass between these two distributed rivers. However, Bananal Island is technically an island as it does not touch the main landmass at any point.
Umananda Island, at 0.02 square kilometres (0.0077 sq mi), is among contenders as the smallest permanently-inhabited river island, or islet, with fixed dwellings. Umananda also lies in the Brahmaputra River. Many as tiny as Umananda or smaller, inhabited, exist on the Amazon basin and Bangladesh. Another island of comparable size to Umananda, Hatfield Island in the Guyandotte River in the U.S. state of West Virginia, has no permanent population, but contains several permanent buildings, namely the K–12 schools serving the city of Logan and its surrounding area plus the main branch of the Logan County public library.
On canalised rivers, such as the Thames and the Seine, one-home islands exist, containing houses constructed of permanent materials. Canals reduce erosion of the islands and in particular limit the height of flash flooding by maintaining substantial "heads" of water through barrages. One-home islands improved by river canals include Monkey, Friday, Holm and D'Oyly Carte islands.

## Lists of river islands
### River islands by area

| Name | Area (km$^2$) | Country | River |
| Bananal Island | 19,162 | Brazil | Araguaia River |
| Riverine Plain, Moulamein, Coleambally, Hay, Balranald | 18,000 | Australia | Formed by the Billabong, Edward, and Murrumbidgee river systems in New South Wales. |
| Tupinambarana | 11,850 | Brazil | Amazon River |
| Bahr al Jabal Island | 7,929 | South Sudan | Bahr al Jabal Bahr el Zeraf |
| Holland/Utrecht | 7,361 | Netherlands | Rhine River IJssel River |
| Ilha Grande de Gurupá | 4,864 | Brazil | Amazon River |
| Margarita Island | 2,832 | Colombia | Magdalena River |
| Uarini Island | 2,339 | Brazil | Uarini River, Amazon River |
| Boven Digul | 2,171 | Indonesia | Digul River, Kawaga River |
| Richards Island | 2,165 | Canada | Mackenzie River |
| Krasnoslobodsk | 2,002 | Russia | Volga River, Akhtuba River |
| Veľký Žitný ostrov | 1,885.2 | Slovakia | Danube, Little Danube |
| Hatiya Island | 1,508.23 | Bangladesh | Meghna River |
| Letea Island | 1,480 | Romania | Danube |
| Camargue | 1,453 | France | Grand Rhone, Petit Rhone |
| Bhola Island | 1,441 | Bangladesh | Meghna River |
| Chongming Island | 1,267 | China | Yangtze River |
| Ile à Morfil | 1,250 | Senegal | Senegal River |
| Zhongshan Island | 1,055.42 | China | Pearl River |
| Dibru Saikhowa | 765 | India | Brahmaputra River |
| Sandwip Island | 762.42 | Bangladesh | Meghna River |
| Great Brăila Island | 720.2 | Romania | Danube |
| Majuli | 553 | India | Brahmaputra River |
| Sumba Island | 500 | Democratic Republic of Congo | Congo River |
| Montreal | 499 | Canada | St. Lawrence River, Rivière des Prairies |
| Szigetköz | 375 | Hungary, Slovakia | Danube |
| Manpura Island | 373 | Bangladesh | Meghna |
| Inhacamba | 340 | Mozambique | Zambezi |
| Hoeksche Waard | 323.74 | Netherlands | Oude Maas, Nieuwe Maas |
| Yangzhong Island | 320 | China | Yangtze River |
| Gunbower Island | 264 | Australia | Murray River |
| Csepel Island | 257 | Hungary | Danube |
| Jésus Island | 242 | Canada | Rivière des Mille Îles, Rivière des Prairies |
| Voorne-Putten | 220 | Netherlands | Oude Maas, Nieuwe Maas |
| Hisingen | 199 | Sweden | Göta älv |
| Mosqueiro | 191 | Brazil | Amazon River |
| Mbamou Island | 180 | Republic of the Congo | Congo River |
| Don Khong | 144 | Laos | Mekong |
| Roberts Island | 133 | United States | San Joaquin River |
| Union Island | 130 | United States | San Joaquin River |
| Davis Island | 120 | United States | Mississippi River |
| Taiama Island | 115.55 | Brazil | Paraguay River |
| Lulu Island | 112.4 | Canada | Fraser River |
| Sarpinskiy Island | 110 | Russia | Volga River |
| Sauvie Island | 84.8 | United States | Columbia River |
| Tunøya | 82 | Norway | Glomma |
| Dordrecht Island | 79.53 | Netherlands | Oude Maas, Hollands Diep |
| Srirangam | 74.4 | India | Kaveri |
| Grand Island | 73.8 | United States | Niagara River |
| Rangitata Island | ~65 | New Zealand | Rangitata River |
| Ostrvo | 60 | Serbia | Danube |
| Hogg Island | 59 | Guyana | Essequibo River |
| Manhattan Island | 59 | United States | Hudson River/East River/Harlem Creek |
| Hengsha Island | 55.74 | China | Yangtze River |
| Rusnė Island | 45 | Lithuania | Neman |
| Wakenaam Island | 45 | Guyana | Essequibo River |
| Belene Island | 41 | Bulgaria | Danube |
| Woodford Island | 37 | Australia | Clarence River |
| Wilhelmsburg | 35.3 | Germany | Elbe |
| Leguan Island | 31 | Guyana | Essequibo River |
| Grave di Papadopoli | 18 | Italy | Piave River |
| Isla Teja | 15 | Chile | Cau-Cau River/Cruces River/Valdivia River |
| Srirangapatna | 13 | India | Kaveri |
| Shivanasamudram | | India | Kaveri |
| Grosse Ile | 25 | United States | Detroit River |
| Inch Clutha | ~24 | New Zealand | Clutha River |
| Khortytsia | 23.59 | Ukraine | Dnieper River |
| Island of Šarengrad | 9 | Disputed (Serbia/Croatia) | Danube |
| Yeouido | 8.4 | South Korea | Han River |
| Tatyshev | 7 | Russia | Yenisey River |
| Sedudu/Kasikili | 5 | Botswana | Cuando River |
| Ada Bojana | 4.81 | Montenegro | Bojana River |
| Hayden Island | 4.4 | United States | Willamette River |
| Nanjido | 2.8 | South Korea | a branch of the Han River |
| Otdyha Island | 2.5 | Russia | Yenisey River |
| Wheeling Island | 1.5 | United States | Ohio River |
| Rŭngrado | 1.3 | North Korea | Taedong River |
| Yanggakdo | 1.2 | North Korea | Taedong River |
| Nakanoshima | 0.7 | Japan | Kyū-Yodo River |
| Zhenbao Island | 0.7 | China | Ussuri River |
| Bhavani Island | 0.53 | India | Krishna River |
| Bamseom | 0.24 | South Korea | Han River |
| Île de la Cité | ~0.2 | France | Seine |
| Nakasu | ~0.2 | Japan | Nakagawa River |
| Prince's Island Park | 0.2 | Canada | Bow River |
| Island of Vukovar | 0.032 | Disputed (Serbia/Croatia) | Danube |
| Umananda Island | 0.02 | India | Brahmaputra River |
| Hatfield Island | 0.17 | United States | Guyandotte River |
| Some Sevit (Gavit, Chavit, Solvit, Yevit) | 0.0104 (0.0048,0.0034,0.0012,0.0008) | South Korea | Han River |
| Pheasant Island | 0.00682 | Condominium between France and Spain | Bidasoa |
   * Note: Includes some river islands that also have an ocean coast.

### Most populous river islands

This list ranks river islands with a population of at least 25,000.
| Name | Population | Area (km$^2$) | Country | City | River |
| Salsette Island | 15,111,974 | 619 | India | Mumbai and Thane | Vasai Creek/Thane Creek |
| Île de Montréal | 1,942,044 (2016) | 499 | Canada | Montreal | Rivière des Prairies/St. Lawrence River |
| Manhattan Island | 1,628,701 (2018) | 59 | United States | New York City | Hudson River/East River |
| Chongming Island | 660,000 (2010) | 1,267 | China | Shanghai | Yangtze River |
| Jésus Island | 422,993 (2016) | 242 | Canada | Laval | Rivière des Mille Îles/Rivière des Prairies |
| Veľký Žitný ostrov | 226,446 (2001) | 1,885 | Slovakia | Bratislava, Komárno, Dunajská Streda and others | Danube, Little Danube |
| Vasilievsky Island | 209,188 (2017) | 10.9 | Russia | St. Petersburg | Bolshaya Neva/Malaya Neva |
| Lulu Island | 198,309 (2016) | 122.4 | Canada | Richmond | Fraser |
| Srirangam | 181,556 (2001) | 13 | India | Srirangam | Kaveri |
| Bangkok Noi | 179,814 (2017) | 18 | Thailand | Bangkok | Chao Phraya River |
| Majuli | 167,304 (2011) | 422 | India | Vaishnavite Shrines | Brahmaputra River |
| Csepel Island | 166,953 (2012) | 257 | Hungary | several | Danube |
| Hisingen | 130,000 | 199 | Sweden | Gothenburg | Göta älv |
| Navotas Island | 117,196 | 1.95 | Philippines | Navotas, Metro Manila | Tullahan River |
| Wilhelmsburg | 49,132 (2006) | 35.3 | Germany | Hamburg | Elbe |
| Yeouido | 30,988 (2006) | 8.4 | South Korea | Seoul | Han River |
| Mosqueiro | 27,000 | 191 | Brazil | Belém | Amazon River |