Chagos Archipelago facts for kids
Map of the Chagos Archipelago
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 Location of the Chagos Archipelago (circled)
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| Geography | |
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| Location | Indian Ocean |
| Coordinates | 6°00′S 71°30′E / 6.000°S 71.500°E |
| Major islands | Diego Garcia, Peros Banhos, Salomon Islands, Egmont Islands |
| Area | 56.13 km2 (21.67 sq mi) |
| Administration | |
| Territory | British Indian Ocean Territory |
| Outer Islands | Chagos Archipelago |
| Demographics | |
| Demonym | Chagossian Chagos Islander Îlois |
| Population | 4,267 (Eclipse Point Town) (2020) |
| Ethnic groups | |
The Chagos Archipelago or Chagos Islands is a group of over 60 islands in the Indian Ocean. They are about 500 kilometres (310 miles) south of the Maldives. These islands form the southernmost part of the Chagos–Laccadive Ridge, which is a long underwater mountain range.
The main islands include the Salomon Islands, Nelsons Island, and Peros Banhos in the north. To the southwest are the Three Brothers, Eagle Islands, Egmont Islands, and Danger Island. The largest island, Diego Garcia, is located southeast of these. Most of the islands are low-lying atolls, which are ring-shaped coral reefs surrounding a lagoon.
From 1715 to 1810, the Chagos Islands were controlled by France. They were managed from Isle de France, which is now called Mauritius. In 1814, under the Treaty of Paris (1814), France gave Isle de France and the Chagos Islands to the United Kingdom.
In 1965, the United Kingdom separated the Chagos Archipelago from Mauritius. They created a new territory called the British Indian Ocean Territory. This was officially set up on 8 November 1965.
The Chagos Islands used to be home to the Chagossians, who spoke a language called Bourbonnais Creole. However, the United Kingdom moved them from the islands between 1967 and 1973. This was done so the United States could build a military base, Naval Support Facility Diego Garcia, on Diego Garcia. Since 1971, only military staff and contractors have lived on Diego Garcia. The Chagossians have not been allowed to return to their homes.
Mauritius has been in a disagreement with the UK over who owns the Chagos Archipelago. Mauritius says the islands are part of its territory. The International Court of Justice (ICJ) and the International Tribunal for the Law of the Sea have both said that the UK should return the islands to Mauritius. In October 2024, the British government announced it would transfer the Chagos Islands to Mauritius. This agreement was signed on 22 May 2025. However, Diego Garcia will remain under British control for at least 99 years.
Contents
Geography of the Chagos Islands
The Chagos Archipelago is about 500 kilometres (310 miles) south of the Maldives. It is also about 1,880 kilometres (1,168 miles) east of the Seychelles.
The land area of all the islands together is about 56.1 square kilometres (21.7 square miles). The largest island, Diego Garcia, is about 32.5 square kilometres (12.5 square miles). If you include the lagoons inside the atolls, the total area is more than 15,000 square kilometres (5,792 square miles). The Great Chagos Bank is the largest atoll structure in the world.
The Chagos group is made of different coralline rock structures. These sit on top of a submarine ridge that runs through the middle of the Indian Ocean. This ridge was formed by volcanoes. The Chagos contains the world's largest coral atoll, the Great Chagos Bank. This atoll has half of all the good quality coral reefs in the Indian Ocean. Because of this, the ecosystems in the Chagos have been strong against climate change.
The biggest individual islands are Diego Garcia, Eagle, Île Pierre, Eastern Egmont, Île du Coin, and Île Boddam. Besides the seven atolls with dry land, there are also nine reefs and banks that are mostly underwater.
Resources of the Chagos Islands
The main natural resources in the Chagos Islands are coconuts and fish. In the past, selling licenses for commercial fishing brought in money for the British Indian Ocean Territory. However, no new licenses have been given since October 2010. This was when a special marine reserve was created where fishing is not allowed.
Most economic activity happens on Diego Garcia, where the UK and US military facilities are located. People from the UK, Mauritius, the Philippines, and the US work there. They build things and provide services for the military base. There are no factories or farms on the islands. All food and other important items are brought in by ship.
Some people want the Chagossians to return to the islands. If they do, they plan to start growing coconuts again and fishing. They also want to develop tourism on the islands.
Before October 2010, certain types of tuna were fished for about two months each year. This was because their migration path took them through Chagos waters. Even though the Chagos Islands are far away, fishing (both legal and illegal) has affected the marine life. There is also a lot of illegal hunting of turtles and other sea animals. Sharks, which are very important for the ocean's food web, have greatly decreased due to illegal fishing.
Climate of the Chagos Islands
The Chagos Archipelago has a tropical oceanic climate. This means it is hot and humid, but the trade winds help to cool it down. The climate has lots of sunshine, warm temperatures, showers, and light breezes.
From December to February is the rainy season, also called the summer monsoon. During this time, there are light winds and more rainfall. From June to September is the drier season, or winter. It has moderate winds, slightly cooler temperatures, and less rainfall. On average, the islands get about 2,600 mm (100 inches) of rain each year.
History of the Chagos Islands
Early History
According to stories from the Southern Maldives, traders and fishermen sometimes got lost at sea and ended up on the Chagos Islands. They were eventually rescued and brought home. However, these islands were thought to be too far from the Maldives to be settled permanently. For many centuries, the Chagos were not settled by Maldivians. But Maldivians did use the Chagos for fishing trips, camping on the islands to catch and dry fish.
In Maldivian stories, the whole group of islands is called Fōlhavahi or Hollhavai.
16th to 19th Century
The first Europeans to find the Chagos Islands were Portuguese explorers. They named the group Bassas de Chagas, which means "wounds" in Portuguese. This referred to the Holy Wounds of Jesus. They also named some atolls, like Diego Garcia. The Portuguese never made these islands part of their empire.
The French were the first European power to claim the Chagos. This happened after they settled on Île Bourbon (now Réunion) in 1665 and Isle de France (now Mauritius) in 1715. In the 1770s, the French started allowing companies to set up coconut oil farms on the Chagos.
On 27 April 1786, Great Britain claimed the Chagos Islands and Diego Garcia. However, the islands were officially given to Britain only in 1815, after Napoleon was defeated. The Chagos Islands were then governed from Mauritius, which was also a British colony.
In 1793, the first successful colony was started on Diego Garcia. Coconut plantations were set up on many islands. The workers were enslaved by the British. They were freed in 1840. Many of these workers and their descendants formed a unique culture called Ilois, which means "Islanders" in a French Creole language.
Commander Robert Moresby mapped the Chagos Islands for the British Admiralty in 1837–38. This was the first time the archipelago was mapped with good accuracy. Moresby also planted 30 breadfruit trees on Diego Garcia.
20th Century
On 31 August 1903, the Chagos Archipelago was separated from the Seychelles and joined to Mauritius.
Before Mauritius became independent, the United Kingdom paid money to the Mauritian government. This was for separating the Chagos Archipelago. The UK also promised that the islands would be returned to Mauritius if they were no longer needed for defense. They also said Mauritius would still be able to use facilities there and have fishing rights.
On 30 December 1966, the United States and the United Kingdom made an agreement. This allowed the United States Armed Forces to use any island in the British Indian Ocean Territory for defense for 50 years, until December 2016. They could also extend this for another 20 years until 2036. As of 2010, only Diego Garcia has been turned into a military base.
Between 1967 and 1973, the people living on the islands were moved to Mauritius and the Seychelles. This was to make space for the joint US–UK military base on Diego Garcia. In March 1971, US naval construction teams arrived on Diego Garcia to build the base. To meet the agreement for an uninhabited island, the coconut farms on Diego Garcia were closed in October of that year.
The farm workers and their families were first moved to other islands in the Chagos. Then, those who wanted to were taken to the Seychelles or Mauritius. In 1972, the UK closed the remaining farms in the Chagos because they were no longer making money. The remaining Ilois were moved to the Seychelles or Mauritius. The Mauritian government asked for payment to accept these islanders. In 1973, the UK agreed and gave them more money to help them settle.
2000–Present
On 1 April 2010, the British government announced the creation of the Chagos Marine Protected Area. This was the world's largest marine reserve, covering 640,000 square kilometres (247,000 square miles). This area is larger than France or the US state of California.
In 2018, Mauritius took the issue of the islands to the International Court of Justice. On 25 February 2019, the International Court of Justice said that the UK's control of the Chagos Archipelago was unlawful. They said the UK should end its control as quickly as possible.
On 22 May 2019, the United Nations General Assembly voted that the Chagos archipelago is part of Mauritius. They asked the UK to withdraw its control within six months. 116 countries voted for this, and only 5 supported the UK.
On 28 January 2021, the United Nation's International Tribunal for the Law of the Sea also said that Britain should hand over the Chagos Archipelago to Mauritius.
On 14 February 2022, a group from Mauritius raised the Mauritian flag on the island of Peros Banhos in the Chagos. This was seen as a formal challenge to British control.
On 3 November 2022, the British Foreign Secretary James Cleverly announced that the UK and Mauritius would start talks about who owns the British Indian Ocean Territory. Both sides agreed that the joint UK/US military base on Diego Garcia would continue to operate.
On 3 October 2024, the UK and Mauritian governments announced they had reached an agreement. The agreement allows the American military base on Diego Garcia to continue. The Chagossian people living in the UK have said they were not included in these talks. However, many Chagossians in Mauritius support Mauritius taking control.
On 27 February 2025, US President Donald Trump said he would support the agreement to transfer control of the Chagos Islands to Mauritius. On 22 May 2025, the UK Prime Minister Kier Starmer signed the formal agreement.
Under the deal, Diego Garcia and its surrounding area will be leased back to the UK. This allows the military base to keep running for the next 99 years, with options to extend. Mauritius will receive annual payments from the UK for this agreement.
Development
The main buildings on the islands are part of the joint defense and Naval Support Facility Diego Garcia. Some old buildings left by the Ilois are still standing but are abandoned. Other uninhabited islands, especially in the Salomon Atoll, are often visited by yachtsmen traveling across the Indian Ocean. However, a permit is needed to visit these outer islands.
People and Language
Chagossians
The original islanders were known as the Ilois. There were about 1,000 of them. They were a mix of African, South Indian, Portuguese, English, French, and Malay backgrounds. They lived simple lives on their isolated islands, working on coconut farms or in fishing. Their language, Chagossian Creole, is still spoken by some of their descendants in Mauritius.
The Ilois who lived on the islands were moved by the US and British governments in the late 1960s and early 1970s. This was done to turn the islands into a military base. Many islanders have asked to return to their homes. The UN General Assembly, the International Court of Justice, and the International Tribunal for the Law of the Sea have all said they have a right to return. However, the US and UK legal systems have not followed these decisions, so the Chagossians remain away from their homeland.
Other People on the Islands
Diego Garcia is the only island in the Chagos that is currently inhabited. It is part of the British Indian Ocean Territory (BIOT). The UK sees it as an Overseas territory of the United Kingdom. The BIOT is governed by a Commissioner appointed by the King.
There are no native people living on the island now. About 1,700 military personnel and 1,500 civilian workers, mostly American, are stationed on Diego Garcia. As of 2012, the islands have about 3,000 people in total, including British government staff and US military personnel.
Ecology of the Chagos Islands
The Chagos Islands, along with the Maldives and Lakshadweep, form a special terrestrial ecoregion. The islands and their surrounding waters are a huge area for environmental protection. This zone is twice the size of the UK's land area.
The deep ocean waters around the Chagos Islands have many different undersea features. These include deep trenches and underwater mountains. These areas likely have many undiscovered species. The rich variety of life in the Chagos archipelago and its waters is what makes it so special. In 2010, 76 species living in Chagos were listed as threatened.
Coral Reefs
The coral reefs here are home to at least 371 types of coral. This includes a special brain coral called Ctenella chagius, which is found only here. In the past, the coral cover was very thick and healthy. However, high water temperatures caused a lot of coral to die in 2015 and 2016. This resulted in more than two-thirds of the corals dying.
Fish Life
The reefs also have at least 784 types of fish that live near the shores. This includes a unique clownfish called Amphiprion chagosensis. There are also many large wrasse and grouper fish that have disappeared from other reefs in the area due to over-fishing.
Besides reef fish, there are also many open-ocean fish like manta rays, whale sharks, other sharks, and tuna. Shark numbers have dropped a lot because of illegal fishing.
Birds
Seventeen types of seabirds nest in large groups on many of the islands. Ten of these islands are important bird areas. This means the Chagos has the most diverse seabird community in this tropical region. Some interesting birds include sooty terns, brown and lesser noddies, wedge-tailed shearwaters, and red-footed boobies. There are not many land birds, and most of them were brought in by humans or came naturally.
Mammals
The Chagos Archipelago has a rich variety of life, including different types of cetaceans (whales and dolphins). This includes three groups of blue whales and many toothed whales like sperm whales and pilot whales. Dugongs used to live here but are now gone. Donkeys that were left behind when the Ilois moved still roam freely.
Turtles
The remote islands are perfect, quiet places for green turtles and hawksbill turtles to lay their eggs. The numbers of both species in Chagos are very important globally. This is because hawksbills are critically endangered and green turtles are endangered. Turtles in Chagos were heavily hunted for two centuries. But now, they and their homes are well protected by the British Indian Ocean Territory government, and their numbers are recovering.
Crustaceans
The coconut crab is the world's largest land arthropod. It can have a leg span of over a meter (3 feet) and weigh up to 4 kilos (9 pounds). When they are young, they act like hermit crabs and use empty coconut shells for protection. But as adults, these giant crabs can climb trees and crack open coconuts with their huge claws. Even though they are found in many places, they are rare in most areas. The coconut crabs on Chagos are one of the most undisturbed groups in the world. They are important for helping to bring back other over-hunted populations in the Indian Ocean.
Insects
113 types of insects have been found on the Chagos Islands.
Plants
The Chagos Islands were first home to plants when there was enough soil to support them. This was probably less than 4,000 years ago. Seeds and spores arrived on the islands by wind, sea, and from passing seabirds. The native flora (plants) of the Chagos Islands is thought to have 41 types of flowering plants and four ferns. It also has many types of mosses and fungi.
Today, the condition of the Chagos Islands' native plants depends on how much each island was used in the past. About 280 types of flowering plants and ferns have been found on the islands now. This is because humans brought in new plants, either by accident or on purpose. Some of these new plants have spread widely and threaten the native ecosystems. Plans are being made to control them. On some islands, native forests were cut down to plant coconut trees for oil. Other islands remain untouched and have many different habitats, including unique Pisonia forests. These untouched islands help us learn how to bring back native plant communities on islands that have been changed a lot. This will help improve the variety of life on the Chagos Islands.
Conservation Efforts
Past Efforts
Different UK governments have supported protecting the environment of the Chagos. They have promised to treat the whole area like a World Heritage Site. In 2003, the UK government created an Environment Protection Zone. This zone extends 200 nautical miles from the islands. On eastern Diego Garcia, the largest island with a UK–US military base, Britain has named the large lagoon and the eastern part of the atoll as an "important wetland" under the Ramsar Convention.
Present Efforts
On 1 April 2010, Britain announced the creation of the Chagos Marine Protected Area. This is the world's largest continuous marine protected reserve, covering 545,000 square kilometres (210,000 square miles).
This was done after groups worked together to protect the rich variety of life in the Chagos Archipelago. The UK government asked for public opinion on how to manage conservation for three months.
On 1 April 2010, the British government officially created the Chagos Archipelago as the world's largest marine reserve. Its protection will be supported by the Bertarelli Foundation.
Permanent Court of Arbitration Ruling
On 18 March 2015, the Permanent Court of Arbitration said that the marine protected area (MPA) created by the UK in April 2010 went against international law. The Prime Minister of Mauritius, Anerood Jugnauth, said this was an important step in Mauritius's fight for control over the Chagos Archipelago. The court found that the UK's promises to Mauritius about fishing rights and oil and mineral rights in the Chagos Archipelago were legally binding. The court also found that the UK's promise to return the Chagos Archipelago to Mauritius when it was no longer needed for defense was legally binding. This means that Mauritius has strong legal rights over the Chagos Archipelago, and the United Kingdom must respect them.
See also
In Spanish: Archipiélago de Chagos para niños
- List of islands in the Chagos Archipelago
- Chagos Archipelago sovereignty dispute
- Expulsion of the Chagossians
- Great Chagos Bank
- Chagos Marine Protected Area
- British Indian Ocean Territory
- Indian Ocean
Images for kids
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Diplomatic cable signed by D. A. Greenhill, 1966, relating to the depopulation of the Chagos Archipelago
