Three-Country Cairn, the boundary cairn at the tripoint, is 10 metres from the shore of Lake Goldajärvi/Koltajauri, and hence arguably a tiny artificial island. Around 14 m2. The lower limit for artificial islands is a matter of definition, because near Haparanda there are boundary poles of less than 0.1 m2.
A lake island at 62°38′28″N 141°00′00″W / 62.641158°N 141°W / 62.641158; -141, north of the Yukon–Alaska Highway border crossing
A lake island at 62°38′14″N 141°00′00″W / 62.637174°N 141°W / 62.637174; -141, just north of the Yukon–Alaska Highway border crossing
Two islands in a small lake at 62°32′18″N 141°00′00″W / 62.538443°N 141°W / 62.538443; -141, 8.2 km south of the Yukon–Alaska Highway border crossing
An island in a small lake on the Okanogan County, Washington/British Columbia border at 49°00′00″N 120°10′23″W / 49°N 120.172980°W / 49; -120.172980
An island in a small lake adjacent to the Milk River at 49°00′00″N 110°32′49″W / 49°N 110.546975°W / 49; -110.546975 in Montana/Alberta
An island[23][24] in Brush Lake at 49°00′00″N 103°58′54″W / 49°N 103.981638°W / 49; -103.981638 in North Dakota/Saskatchewan
Two islands[25][26] in Boundary Lake at 49°00′00″N 100°13′02″W / 49°N 100.217095°W / 49; -100.217095, in North Dakota/Manitoba
An island[27][28] in Lake Metigoshe at 49°00′00″N 100°21′14″W / 49°N 100.353901°W / 49; -100.353901 in North Dakota/Manitoba
An islet[29][30] east of Ross Lake at 49°00′00″N 100°17′56″W / 49°N 100.298939°W / 49; -100.298939 in North Dakota/Manitoba
An island[31][32] in a small lake on the Rolette County, North Dakota/Manitoba border at 49°00′00″N 100°00′47″W / 49°N 100.013149°W / 49; -100.013149
An island[33][34] in a small lake on the Towner County, North Dakota/Manitoba border at 49°00′00″N 99°13′05″W / 49°N 99.218163°W / 49; -99.218163
An island[35][36] in a small lake on the Cavalier County, North Dakota/Manitoba border at 49°00′00″N 98°32′29″W / 49°N 98.541357°W / 49; -98.541357
An islet[37] in a small reservoir (when filled) just east of the Maidaport of entry on North Dakota Highway 1 at 49°00′01″N 98°21′25″W / 49.000253°N 98.356943°W / 49.000253; -98.356943, North Dakota/Manitoba
Pine and Curry Island[38] in Lake of the Woods on the Minnesota/Ontario border at 48°52′37″N 94°41′02″W / 48.876967°N 94.683964°W / 48.876967; -94.683964
Seaway Island in Lake St. Clair on the Michigan/Ontario border at 42°31′25″N 82°40′39″W / 42.523639°N 82.677582°W / 42.523639; -82.677582
An island in a small lake on the border of Maine/New Brunswick at 46°00′18″N 67°46′52″W / 46.004988°N 67.7810°W / 46.004988; -67.7810, southeast of Hodgdon, Maine
The border between Austria and Hungary cuts across the Neusiedler See/Fertő tó, where the water level fluctuates, sometimes exposing island flats which straddle the border.
The lower reaches of the Ganges,[83]Teesta,[84] and Brahmaputra[85] Rivers, approaching the Ganges Delta, are braided and contain numerous sand islands called chars.[86] These can be large and inhabited but are impermanent. At any given time, several are likely to straddle the border between India (Assam and West Bengal) and Bangladesh, though this border is not fully specified.
An islet in the Uutuanjoki, between Finland and Norway, at 69°34′47″N 29°13′54″E / 69.579665°N 29.231701°E / 69.579665; 29.231701.
An islet in the Vadet near Tunnsjø, between Norway and Sweden, at 64°38′40″N 13°42′38″E / 64.644443°N 13.71056°E / 64.644443; 13.71056.
An islet on the western side of the golf course that straddles the municipalities of Tornio in Finland, and Haparanda in Sweden, at 65°51′41″N 24°07′47″E / 65.861513°N 24.129624°E / 65.861513; 24.129624.
Nokiel and another unnamed islet in the Dunajec river, between Slovakia and Poland, at 49°23′54″N 20°21′35″E / 49.3984°N 20.359726°E / 49.3984; 20.359726.[88]
9 islands serially located in the Clarence River on the Alaska North Slope near Demarcation Bay; northernmost at 69°37′00″N 141°00′00″W / 69.616789°N 141°W / 69.616789; -141, southernmost at 69°33′26″N 141°00′00″W / 69.557094°N 141°W / 69.557094; -141
One or more islands in Trail Creek at 68°52′54″N 141°00′00″W / 68.881754°N 141°W / 68.881754; -141, northeast of Arctic Village, Alaska
An island in Mancha Creek at 68°39′50″N 141°00′00″W / 68.663957°N 141°W / 68.663957; -141, northeast of Arctic Village, Alaska
6 (or more) islands in bifurcated flow in the Firth River at 68°38′30″N 141°00′00″W / 68.641781°N 141°W / 68.641781; -141, northeast of Arctic Village, Alaska
An island in Sunaghun Creek at 67°25′34″N 141°00′00″W / 67.426117°N 141°W / 67.426117; -141, near its mouth at the Porcupine River, downstream of Old Crow, Yukon
An island in the watershed of the Bluefish River at 66°50′17″N 141°00′00″W / 66.838155°N 141°W / 66.838155; -141, east of Chalkyitsik, Alaska and 15 km WWSW of Bluefish Lake, Yukon
An island in Fort Creek at 66°45′32″N 141°00′00″W / 66.759004°N 141°W / 66.759004; -141, east of Chalkyitsik, Alaska
An island in the Black River (Salmon Fork) at 66°32′37″N 141°00′00″W / 66.543661°N 141°W / 66.543661; -141, east of Chalkyitsik, Alaska
An island in Beaver Creek at 62°13′39″N 141°00′00″W / 62.227460°N 141°W / 62.227460; -141, southwest of Beaver Creek, Yukon
Two islands in Klehini River at 59°26′53″N 136°21′55″W / 59.448142°N 136.365213°W / 59.448142; -136.365213, near Klukwan, Alaska
11 (or more) islands in bifurcated river flow on Whiting River at 58°11′06″N 133°13′16″W / 58.184862°N 133.221034°W / 58.184862; -133.221034, upstream of Gilbert Bay, which empties into Stephens Passage
Two islands in Stikine River at 56°39′31″N 131°50′55″W / 56.658546°N 131.848698°W / 56.658546; -131.848698, downstream of Great Glacier, Yukon
Two islands on the Maine/New Brunswick border southeast of Monticello, Maine (46°16′22″N 67°46′55″W / 46.272890°N 67.782°W / 46.272890; -67.782 and 46°16′20″N 67°46′55″W / 46.272293°N 67.782°W / 46.272293; -67.782) that are formed by the forks of a stream that rises from Gentle Lake in Maine, then flows into the North Branch–Meduxnekeag River.
Historically divided islands
Other islands have been divided by international borders in the past but they are now unified.
The definite borders of modern nation states do not apply in other forms of societal organisation, where "divided" islands may consequently be less noteworthy. For example, in Ancient Greece, the island of Euboea was divided among several city-states, including Chalcis and Eretria; and before its settlement by Europeans, the Island of Tasmania was divided among nine indigenous tribes.
Boundary Islet – divided between the colonies of Victoria (part of New South Wales until 1851) and Tasmania (known as Van Diemen's Land until 1856); remained separated between two Australian states
Ternate – divided between the Spanish Empire allied with Tidore, and the Dutch Republic allied with the Sultan of Ternate from 1607 through 1663. Later, Ternate has successive been owned by the Netherlands, the Japanese Empire (1942–1945), Netherlands again, and the independent country of Indonesia, beginning in 1949.
Saint Kitts – Divided between Great Britain and the French Empire in 1628. "The island fell to the French in April 1666, but by the Treaty of Utrecht, April 11, 1713, it was yielded entirely to the British crown."[94] Then it became part of the British Empire for about 250 years, and finally part of the independent country of Saint Kitts and Nevis. At various times of war in the Caribbean Sea, either France or Great Britain occupied all of Saint Kitts both before and after 1713.
Frijoles Island within Gatun Lake in the former Panama Canal Zone was split between the United States and Panama on 1 October 1979, the date that the 1977 Panama Canal Treaty took effect. Much of the former Canal Zone area was transferred to Panama on that day. The Panama Railroad served as the new border in an area where it crosses Gatun Lake via a causeway, with the railroad bisecting Frijoles Island. The entire island transferred to exclusive Panamanian jurisdiction on 31 December 1999.[97][98]
The small middle island of Las Tres Hermanas ("The Three Sisters") off the Pacific coast of Panama City was split between the U.S. Panama Canal Zone and Panama by the Taft Agreement on 12 December 1904. The entire island was placed in the Canal Zone on 11 February 1915. Today the Cinta Costera lies on top of it.
Popes Folly Island in Passamaquoddy Bay between the United States (Maine) and Canada (New Brunswick) had been divided prior to the 1908 border treaty between the U.S. and Great Britain.[99][100]
The small Bogomerom Archipelago of islets in Lake Chad was formerly divided between Chad and Nigeria.[101] The water level of Lake Chad has historically varied a lot, but this level has fallen so low that these islets are now part of the mainland of Africa.
Subnationally divided islands
There are islands that lie across different provinces or states of the same country.
^Central America and Caribbean: Haiti, CIA World Factbook
^Central America and Caribbean: Dominican Republic, CIA World Factbook
^The tip of Cape Muzon was established as the "point of commencement" of the international boundary with Alaska in the Anglo-Russian Convention of 1825. A Court of Arbitration in 1903 ruled that Point "A" (54°39′43.993″N 132°41′3.093″W / 54.66222028°N 132.68419250°W / 54.66222028; -132.68419250) was the initial point of this boundary. Canada has accepted this as a demarcated boundary; however, the U.S. disputes that Point "A" is a boundary point.
^Davidson, George (1903). The Alaska Boundary. San Francisco: Alaska Packers Association. pp. 79–81, 129–134, 177–179, 229.
^"International Boundary Commission definition of the Canada/US boundary in the NAD83 CSRS reference frame". Archived from the original on 2011-07-26. Retrieved 2015-03-21.
^White, James (1914). Boundary Disputes and Treaties. Toronto: Glasgow, Brook & Company. pp. 936–958.
^Gray, David H. (Autumn 1997). "Canada's Unresolved Maritime Boundaries" (PDF). IBRU Boundary and Security Bulletin. p. 61. Retrieved 2015-03-21.
^Margedant, Udo; Thomas Ellerbeck (1991). Politische Landeskunde Mecklenburg-Vorpommern (in German). Mecklenburg-Vorpommern: Landeszentrale für politische Bildung. p. 89.
^Map of Inakari, the Finnish part of Kataja 65°41′59″N 24°10′08″E / 65.699644°N 24.168781°E / 65.699644; 24.168781
^Giosan, Liviu; Donenelly, Jeffrey P.; Vespremeanu, Emil; Bhattacharya, Janok P.; Olariu, Cornel; Buonaiuto, Frank S. (2005). "River Delta Morphodynamics: Examples from the Danube Delta" (PDF). River Deltas—Concepts, Models, and Examples (Special Publication No. 83). Society for Sedimentary Geology: 403–405. ISBN 1-56576-113-8.
^Map of divided island southeast of Peräluoto 60°32′09″N 27°46′41″E / 60.535716°N 27.778154°E / 60.535716; 27.778154
^Retrieved 19 June 2013 Bing Maps
^Retrieved 19 June 2013 North Dakota Hub Explorer Archived 2013-05-08 at the Wayback Machine
^Retrieved 19 June 2013 Bing Maps
^Retrieved 19 June 2013 North Dakota Hub Explorer Archived 2013-05-08 at the Wayback Machine
^Retrieved 19 June 2013 Bing Maps
^Retrieved 19 June 2013 North Dakota Hub Explorer Archived 2013-05-08 at the Wayback Machine
^Retrieved 19 June 2013 Bing Maps
^Retrieved 19 June 2013 North Dakota Hub Explorer Archived 2013-05-08 at the Wayback Machine
^Retrieved 19 June 2013 Bing Maps
^Retrieved 19 June 2013 North Dakota Hub Explorer Archived 2013-05-08 at the Wayback Machine
^Retrieved 19 June 2013 Bing Maps
^Retrieved 19 June 2013 North Dakota Hub Explorer Archived 2013-05-08 at the Wayback Machine
^Retrieved 19 June 2013 Bing Maps
^Retrieved 19 June 2013 North Dakota Hub Explorer Archived 2013-05-08 at the Wayback Machine
^Retrieved 19 June 2013 North Dakota Hub Explorer Archived 2013-05-08 at the Wayback Machine
^"Pine and Curry Island SNA". Minnesota Department of Natural Resources. Retrieved 2021-04-27.
^Jacques Boisvert. "Province Island". Retrieved 2006-11-04. It is the largest island in Lake Memphremagog, being 77 acres, of which 7 acres, are in the United States.
^"Norway-Russia Boundary Map: Boundary markers 167–177: Sandneset-Klistervatn" (in Norwegian and Russian). Norwegian Boundary Commission for the Norway-Russia border. Archived from the original on 2007-08-14. Retrieved 2007-09-25. — boundary markers #169–172
^"Norway-Russia Boundary Map: Boundary markers 7–14: Grenseberg-Ødevasselva" (in Norwegian and Russian). Norwegian Boundary Commission for the Norway-Russia border. Archived from the original on 2007-08-14. Retrieved 2007-09-25. — boundary markers #12–13 (Korkeasaari) & #14 (unnamed islet)
^Portion of Nuijamaanjärvi with Äikkäänniemi marked from Citizen's Mapsite of Finland.
^Portion of Yla-Tirja with divided islands at markers 93 (Suursaari) and 94 (smaller island) from Citizen's Mapsite of Finland.
^Portion of Melaselänjärvi showing Tarraassiinsaari and Härkäsaari from Citizen's Mapsite of Finland.
^Portion of Melaselänjärvi showing Kiteensaari from Citizen's Mapsite of Finland.
^Portion of Kokkojärvi showing Rajasaari from Citizen's Mapsite of Finland.
^Portion of Vuokkijärvi showing Kalmasaari from Citizen's Mapsite of Finland.
^Portion of Hietajärvi showing Varposaari from Citizen's Mapsite of Finland.
^Portion of Parvajärvi showing Parvajärvensaari from Citizen's Mapsite of Finland.
^Office of the Geographer, Bureau of Intelligence and Research (1967-02-01). International Boundary Study No. 74: Finland–U.S.S.R. boundary (PDF). United States Department of State. p. 21. Archived from the original (PDF) on 2006-09-16. Hence the frontier runs...to a point on a small unnamed island in Lake Pukarinjarvi between the cape west of the village of Laitela and the Niittysaaryi island.
^Portion of Pukarijärvi with Keuhkosaari marked from Citizen's Mapsite of Finland.
^International Boundary Study No. 74, page 22. ""The frontier follows the creek down to Lake Onkamojarvi, intersects the small island of Siiheojansuusaai and proceeds in a straight line to the small island of Tossensaari."
^Portion of Onkamojärvi from Citizen's Mapsite of Finland (Siiheojansuusaari is IV/179; Tossonsaari is IV/180)
^Portion of Kivisarijärvi with divided island marked from Citizen's Mapsite of Finland. 69°44′09″N 28°52′56″E / 69.735926°N 28.88235°E / 69.735926; 28.88235
^Neighborhood of boundary marker 347A, with divided island marked from Citizen's Mapsite of Finland. 69°53′N 28°18′E / 69.89°N 28.3°E / 69.89; 28.3
^Verified at Norwegian state cartographic agency website (in English, Norwegian, and Northern Sami)
^Krogh, Jan S. "Lake Druksiai". Retrieved 2006-12-10. The international border is marked on the map.
^"World Lakes Database: LAKE DRUKSIAI". International lakes environment committee. Archived from the original on 2007-03-12. Retrieved 2006-12-10. Number of main islands (name and area): Zamok (0.26 km2), Sosnovec (0.048 km2), Utovec (0.0088 km2) and 5 nameless islands.
^"Bathymetric map of Lake Drūkšiai". International lakes environment committee. Archived from the original (GIF) on 8 January 2006. Retrieved 2006-12-10. Sosnovec is named on this map.
^Coordinates of Lake Drūkšiai:55°37′N 26°38′E / 55.617°N 26.633°E / 55.617; 26.633
^"Visor cartográfico de Chile". Retrieved 2020-07-07.
^Office of the Geographer, Bureau of Intelligence and Research (1976-02-20). International Boundary Study No. No. 154 – Djibouti – Ethiopia Boundary (PDF). United States Department of State. p. 8. Archived from the original (PDF) on 2013-11-09. From Monument No. 53 on the south bank of Lake Abbe, the border crosses the lake from south to north continuing in a straight line for 30 kilometers. It cuts across the islet of hill 255 off Cape Aleilou.
^"Map of Commune of Schengen" (PDF). Commune of Schengen. Archived from the original (PDF) on 2007-06-15. Retrieved 2006-12-10.. Coordinates: 49°28′08″N 6°22′05″E / 49.46894°N 6.36812°E / 49.46894; 6.36812
^ a bДополнительное соглашение между Российской Федерацией и Китайской Народной Республикой о российско-китайской государственной границе на ее Восточной части Archived 2011-08-12 at the Wayback Machine от 14 октября 2004 года.
^The northern shore of Corocoro is on the open ocean, but it is not truly a sea island as the southern boundary is a freshwater channel. The island is claimed in its entirety by Venezuela. 8°31′01″N 60°04′59″W / 8.517°N 60.083°W / 8.517; -60.083
^Office of the Geographer, Bureau of Intelligence and Research (1985-04-15). International Boundary Study No. 174: Brazil – Colombia boundary (PDF). United States Department of State. p. 8. Archived from the original (PDF) on 2006-09-16. The final report allocated all river islands on the basis of the thalweg with the exception of San Jose Island on the Rio Negro which was split between Brazil (southern half) and Colombia. Co-ordinates:1°13′42″N 66°51′17″W / 1.228401°N 66.854811°W / 1.228401; -66.854811
^Barros, Vicente (Coordinator) Impact Of Global Change On The Coastal Areas Of The Rio De La Plata: Sea Level Rise And Meteorological Effects. Page 7[permanent dead link]
^Chowdhury, Sifatul Quader; Chowdhury, Masud Hasan (2012). "Char". In Islam, Sirajul; Jamal, Ahmed A. (eds.). Banglapedia: National Encyclopedia of Bangladesh (Second ed.). Asiatic Society of Bangladesh.
^Office of the Geographer, Bureau of Intelligence and Research (1964-11-23). International Boundary Study No. 41: Greece – Turkey boundary (PDF). United States Department of State. p. 7. Archived from the original (PDF) on 2009-03-16. Returning to the median of the Maritsa, [...] the boundary continues [...] to boundary marker No. 24 on the northern end of an island designated "Q". Thence, the boundary line extends a distance of 800.5 feet to marker No. 25 near the center, thence a distance of 1,804 feet to marker No. 26 on the southwestern extremity of island "Q".
^"Zmluva medzi Poľskou republikou a Slovenskou republikou o zmenách priebehu štátnej hranice a schválení hraničnej dokumentácie (AGREEMENT between the Polish Republic and the Slovak Republic on changes of the boundary line and the approval of border documentation, drawn up in the Old Ľubovňa on 29 July 2002.)". Dziennik Ustaw (in Slovak) (203). Prime Minister of Poland: 1686. 2005. Archived from the original on 2013-11-09. Retrieved 28 May 2013.
^"Visor cartográfico de Chile". Retrieved 2020-07-07.
^"Visor cartográfico de Chile". Retrieved 2020-07-07.
^"NDGIS North Dakota Hub Explorer". Archived from the original on 8 May 2013. Retrieved 19 June 2013.
^ Dookhan, Isaac (1994). A History of the Virgin Islands of the United States. Kingston, Jamaica: Canoe Press. ISBN 9789768125057., pp. 40-49
^Ramerini, Marco. "Dutch and Courlanders in Tobago: A history of the first settlements, 1628–1677". Archived from the original on 2007-09-28. Retrieved 2007-10-01.
^Ireland, Gordon (1941). Boundaries, possessions, and conflicts in Central and North America and the Caribbean. New York: Octagon Books. p. 344.
^Wolff, Sir Henry Drummond (1855). The island empire, or, Scenes of the first exile of the Emperor Napoleon I: together with a narrative of his residence on the island of Elba, taken from local information, the papers of the British resident, and other authentic sources. Bosworth. pp. 304–322. Retrieved 27 August 2011.
^Frey, Linda; Frey, Marsha (1995). The treaties of the War of the Spanish Succession: an historical and critical dictionary. Greenwood Publishing Group. pp. 421–2. ISBN 978-0-313-27884-6. Retrieved 27 August 2011.
^United States. Central Intelligence Agency. (1987). "Land and waters of the Panama Canal Treaty (map)". Washington, D.C. Archived from the original on 2016-03-04. Retrieved 2015-07-15.
^"Carte IV. Aires de terre et d'eau mises à disposition du fonctionnement et de la défense du canal de Panama par le traité relatif au canal de Panama du 7 septembre 1977". Dirección ejecutiva para los asuntos del tratado (DEPAT). Ciudad de Panama. 1981. Retrieved 2015-07-11.
^A treaty between Great Britain and the United States providing for the more complete definition and demarcation of the international boundary between the Dominion of Canada and the United States. 1908. pp. 1–3. hdl:2027/hvd.32044086241809.
^"Eastport Quadrant 15x15 grid map". United States Geological Survey. 1907. Archived from the original on 2017-08-03. Retrieved 2016-02-07. (download)
^Office of the Geographer (June 1969). "Chad-Nigeria boundary". United States Department of State. Archived from the original (JPEG) on 2007-06-15. Retrieved 2006-12-06.