Mapping the World’s Islands

Mark Altaweel


There are over 300,000 islands in the world and most of these are poorly documented or generally unknown. A new United States Geological Survey (USGS) and Esri project has now mapped 340,691 islands of the Earth’s islands and created a GIS dataset that is publicly available.

World Islands GIS Data

As Charles Darwin noted, islands are incredibly diverse and demonstrate how life can exist in the most isolated locations. They also contain many unique cultures and languages, making them socially important. Islands are also all landmasses on our planet. Increasingly, islands are under threat from climate change and sea level rise in particular.

The vast majority of islands are small and many are uninhabited. Documenting them might be the only way some of these islands will be remembered in the future.

Global Islands Explorer

The USGS and Esri effort has created the Global Islands Explorer (GIE), which provides vectorized Global Shoreline Vector (GSV) data available to the public to access.

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In this database,  every island, including large continental landmasses and very small islands (e.g., Key West), is documented with satellite data, topography, or other raster data as background, and information about the islands, including area, names, coastlines, tectonic plates they belong to, and other information provided.

Islands are classified as small areas (less than 1 KM2), where there are 318,868 islands in this category, while the remainder (21,818) are classified as large.

The project was carried out in conjunction with the Geo Global Ecosystem Initiative (GEO ECO), where geospatial data were standardized to this initiative and help classify islands according to their ecosystems, which are: coastal land areas, nearshore coastal waters, and offshore coastal waters.[1]

Screenshot of the global islands explorer, a mapping application that can be accessed via a browser.
Screenshot of the global islands explorer, a mapping application that can be accessed via a browser.

Applications of Mapped Island Data

While the GIE effort is mostly about documentation, application could potentially be used in a variety of areas. For instance, better understanding vulnerabilities of island populations and migrants in the face of sea level change could be on area.[2] It also allows a better understanding of biodiversity, including natural resource found on islands.

The initiative also potentially could be used to identify how historically populations may have moved in remote regions such as the southern Pacific and Coral Sea, where Polynesians migrated along an enormous route where they eventually inhabited many islands in that region.[3]

For future applications, emergency planning and preparation, as demonstrated by the Haiti Earthquake of 2010, could be useful with better geographic knowledge.[4] These applications could also aid in economic development and investing, where knowledge about remote islands and regions could enable overall better development that could be more sustainable and suited for a given region.

So far, few projects have developed from using the GIE effort’s database, although this might change soon. Additionally, the effort is attempting to put more information, particularly about the small islands that constitute the vast majority of islands, on its database. In some regions, names of islands, for instance, are still unknown.

The GIE effort is unique in that it is the first time all of the Earth’s islands are being mapped. While every landmass can be considered to be an island, the vast majority of islands are unknown or very little information exists about them. Islands can range from atolls to large continents. With satellite imagery, they are easier than ever to record, but this effort also requires data from these islands.

Crowdsource data and other initiatives may help to populate more data about some of the most remote islands. The effort can in the near future provide a variety of benefits for understanding the past of these islands to better planning for their futures.


[1]    For more information on the GIE database, see: Additionally, there is an academic publication on the effort that details the effort:  Sayre, R., S. Noble, S. Hamann, R. Smith, D. Wright, S. Breyer, K. Butler, K. Van Graafeiland, C. Frye, D. Karagulle, D. Hopkins, D. Stephens, K. Kelly, Z, basher, D. Burton, J. Cress, K. Atkins, D. van Sistine, B. Friesen, B. Allee, T. Allen, P. Aniello, I Asaad, M. Costello, K. Goodin, P. Harris, M. Kavanaugh, H. Lillis, E. Manca, F. Muller-Karger, B. Nyberg, R. Parsons, J. Saarinen, J. Steiner, and A. Reed. 2018. A new 30 meter resolution global shoreline vector and associated global islands database for the development of standardized global ecological coastal units. Journal of Operational Oceanography – A Special Blue Planet Edition. DOI:10.1080/1755876X.2018.1529714.

[2]    For more on migrants from islands affected by environmental change, see:  Mayer, B., Crépeau, F. 2017. Research Handbook on Climate Change, Migration and the Law. Edward Elgar Publishing.

[3]    For more on island hoping migration, see:  Norman, K. 2018. Island-hopping study shows the most likely route the first people took to Australia. The Conversation, 2 April 1-4.

[4]    As an example of how geography of a large island could help in planning for disaster relief, see:  Zook, M., Graham, M., Shelton, T., Gorman, S., 2010. Volunteered Geographic Information and Crowdsourcing Disaster Relief: A Case Study of the Haitian Earthquake. World Medical & Health Policy 2, 6–32.

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About the author
Mark Altaweel
Mark Altaweel is a Reader in Near Eastern Archaeology at the Institute of Archaeology, University College London, having held previous appointments and joint appointments at the University of Chicago, University of Alaska, and Argonne National Laboratory. Mark has an undergraduate degree in Anthropology and Masters and PhD degrees from the University of Chicago’s Department of Near Eastern Languages and Civilizations.