2020 Edition

Background

Formerly administered as part of the British Crown Colony of Mauritius, the British Indian Ocean Territory (BIOT) was established as an overseas territory of the UK in 1965. A number of the islands in the territory were later transferred to the Seychelles when it gained independence in 1976. Subsequently, BIOT has consisted of the six main island groups that make up the Chagos Archipelago. Only Diego Garcia, the largest and most southerly of the islands, is inhabited. It contains a joint UK-US naval support facility and hosts one of four dedicated ground antennas that assist in the operation of the Global Positioning System (GPS) navigation system -- the others are on Kwajalein (Marshall Islands); at Cape Canaveral, Florida (US); and on Ascension Island (Saint Helena, Ascension, and Tristan da Cunha). The US Air Force also operates a telescope array on Diego Garcia as part of the Ground-Based Electro-Optical Deep Space Surveillance System (GEODSS) for tracking orbital debris, which can be a hazard to spacecraft and astronauts. Between 1967 and 1973, the former agricultural workers who lived on the islands were relocated, primarily to Mauritius but also to the Seychelles. Negotiations with the UK between 1971 and 1982 resulted in the establishment of a trust fund to compensate the displaced islanders, known as Chagossians. Beginning in 1998, the islanders pursued a series of lawsuits against the British Government, seeking further compensation and the right to return to the territory. British court rulings in 2006 and 2007 invalidated immigration policies that had excluded the islanders from the archipelago, but in 2008, the House of Lords -- the final court of appeal in the UK -- ruled in favor of the British Government by overturning the lower court rulings and finding no right of return for the Chagossians. In 2015, the Permanent Court of Arbitration unanimously held that the marine protected area that the UK declared around the Chagos Archipelago in 2010 violated the UN Convention on the Law of the Sea. In 2019, the International Court of Justice ruled in an advisory opinion that Britain’s decolonization of Mauritius was not lawful because of continued Chagossian claims. A non-binding 2019 UN General Assembly vote demanded that Britain end its “colonial administration” of the Chagos Archipelago and that it be returned to Mauritius. On 22 May 2025, the United Kingdom and Mauritius signed an agreement that will lead to the transfer of sovereignty of the Chagos Archipelago to Mauritius. Under the agreement, the United Kingdom will lease Diego Garcia from Mauritius for 99 years and maintain full operational control of the joint UK-US military base.

Area

land

60 sq km (44 Diego Garcia)

total

60 sq km

water

54,340 sq km

Area - comparative

land area is about one-third the size of Washington, D.C.

Climate

tropical marine; hot, humid, moderated by trade winds

Coastline

698 km

Elevation

highest point

ocean-side dunes on Diego Garcia 9 m

lowest point

Indian Ocean 0 m

Geographic coordinates

6 00 S, 71 30 E

Geography - note

note 1: archipelago of 55 islands; Diego Garcia, the largest and southernmost island, occupies a strategic location in the central Indian Ocean note 2: Diego Garcia is the only inhabited island of the BIOT

Land boundaries

total

0 km

Land use

agricultural land

0% (2018 est.)

agricultural land: arable land

arable land: 0% (2018 est.)

agricultural land: permanent crops

permanent crops: 0% (2018 est.)

agricultural land: permanent pasture

permanent pasture: 0% (2018 est.)

forest

0% (2018 est.)

other

100% (2018 est.)

Location

archipelago in the Indian Ocean, south of India, about halfway between Africa and Indonesia

Map references

Political Map of the World

Maritime claims

Environment (Protection and Preservation) Zone

200 nm

territorial sea

12 nm

Natural hazards

none; located outside routes of Indian Ocean cyclones

Natural resources

coconuts, fish, sugarcane

Terrain

flat and low coral atolls (most areas do not exceed 2 m, or 6.6 ft, in elevation); sits atop the submarine volcanic Chagos-Laccadive Ridge

Population

total

no permanent inhabitants

Capital

geographic coordinates

 7 18S, 12 24E

name

administered from London; often regarded as being on Diego Garcia

time difference

UTC+6 (12 hours ahead of Washington, DC, during Standard Time)

Constitution

history

British Indian Ocean Territory (Constitution) Order 2004

Country name

abbreviation

BIOT

conventional long form

British Indian Ocean Territory

conventional short form

none

etymology

self-descriptive name specifying the territory's affiliation and location

Dependency status

overseas territory of the UK; administered by a commissioner, resident in the Foreign, Commonwealth, and Development Office in London

Diplomatic representation from the US

embassy

none (overseas territory of the UK)

Diplomatic representation in the US

none (overseas territory of the UK)

Executive branch

cabinet

NA

chief of state

King CHARLES III (since 8 September 2022)

election/appointment process

the monarchy is hereditary; commissioner and administrator appointed by the monarch

head of government

Commissioner Nishi DHOLAKIA (since 16 December 2024); Administrator Bob FAIRWEATHER; both reside in the UK and are represented by Commander Andrew WILLIAMS, RN, the officer commanding British Forces on Diego Garcia (since January 2025)

Flag

description: white with six wavy blue horizontal stripes; the UK flag is in the upper-left quadrant; the striped section has a palm tree and yellow crown (the territory's symbols) centered on the right half of the flag meaning: the wavy stripes represent the Indian Ocean; the six blue stripes may stand for the six main atolls of the archipelago

International organization participation

UPU

Legal system

the laws of the UK apply

National anthem(s)

history

official anthem, as a UK overseas territory

lyrics/music

unknown

title

"God Save the King"

Economic overview

small island territory economy; economic activity mainly on Diego Garcia with national military installations; recently settled disputes with Mauritius have increased oil exports; established marine reserve has limited commercial fishing

Exchange rates

the US dollar is used

Exports - commodities

fish (2023)

Exports - partners

Singapore 86%, Pakistan 8%, USA 1%, South Africa 1%, Czechia 1% (2023)

Imports - commodities

refined petroleum, animal products, aluminum structures, insulated wire, prefabricated buildings (2023)

Imports - partners

Greece 52%, Singapore 38%, USA 4%, Panama 2%, UAE 2% (2023)

Broadcast media

Armed Forces Radio and Television Service (AFRTS) broadcasts over 3 frequencies for US and UK military personnel stationed on the islands

Communications - note

Diego Garcia hosts one of four dedicated ground antennas that assist in the operation of the Global Positioning System (GPS) navigation system (the others are on Kwajalein (Marshall Islands), at Cape Canaveral, Florida (US), and on Ascension Island (Saint Helena, Ascension, and Tristan da Cunha))

Internet country code

.io

Airports

1 (2025)

Ports

key ports

Diego Garcia

large

0

medium

0

ports with oil terminals

1

small

0

total ports

1 (2024)

very small

1

Military - note

defense is the responsibility of the UK; on 22 May 2025, the United Kingdom and Mauritius signed an agreement that will lead to the transfer of sovereignty of the Chagos Archipelago to Mauritius; under the agreement, the United Kingdom will lease Diego Garcia from Mauritius for 99 years and maintain full operational control of the joint UK-US military base

Military and security forces

no regular military forces

Environmental issues

wastewater discharge into the lagoon on Diego Garcia