British Indian Ocean Territory
Source: gov.uk (2025-03-10)

The British Indian Ocean Territory (BIOT) is administered from London. We work to support security and good governance, and preserve marine environment and historical heritage.

The British Indian Ocean Territory has been under continuous British sovereignty since 1814. BIOT is close to the very centre of the Indian Ocean, mid-way between Tanzania and Indonesia. Its nearest neighbours are the Maldives and Sri Lanka.

The Territory covers 640,000 square kilometres of ocean but the land area is only 60 square kilometres. The largest and most southerly of the 58 islands, Diego Garcia, accounts for more than half the land area. There is no native population on the islands.

BIOT is constitutionally distinct and separate from the UK, with its own laws and Administration. The constitutional arrangements for BIOT are set out in the British Indian Ocean Territory (Constitution) Order 2004 and related instruments. The Territory is administered from London, by a Commissioner appointed by The Queen, who is assisted by a Deputy Commissioner and Administrator. The 2004 Order gives the Commissioner power to make laws for the peace, order and good governance of BIOT.

In 1966 the UK agreed with the USA to make BIOT available for the defence purposes of the 2 countries. The US presence on the island of Diego Garcia is governed by a series of agreements called an Exchanges of Notes. From this, the overarching agreement sets out that the whole Territory should be made available for UK and US defence purposes.

The Government of the British Indian Ocean Territory website (https://biot.gov.io/) provides information relating to the BIOT Government in a single place. It includes the latest news and information, including details on:
- all the current legislation for the Territory
- the Official Gazette detailing orders and appointments
- information on Heritage visits
- information on BIOT stamps and coins
- environment, science and the Marine Protected Area (MPA)
Environment

The wildlife and environment of the British Indian Ocean Territory are exceptional. The Territory has the greatest marine biodiversity in the UK and its Overseas Territories, as well as some of the cleanest seas and healthiest reef systems in the world which are protected by the largest no-take Marine Protected Area (MPA) in the Indian Ocean.

BIOT has some unique terrestrial habitats. All islands are formed of low-lying coral with a typical maximum elevation of 1 to 2 metres above sea level. BIOT is also home to the world’s biggest arthropod, the coconut crab, which can reach up to 1 metre across, with densities on Diego Garcia amongst the highest globally.

BIOT represents a nearly untouched ‘ocean observatory’ which provides researchers across the world with a place like no other for scientific research. It also provides a testing ground for new environmental management techniques with significance to other protected areas around the world.

The UK remains committed to implementing the United Nations Convention on the Law of the Sea (UNCLOS) Arbitral Award of 2015.

Science

The rich biodiversity and near-pristine environment of the British Indian Ocean Territory (BIOT) makes it a unique location for scientific study. Scientific expeditions from a wide range of disciplines and operating in both the terrestrial and marine environments, have visited the Territory. These expeditions have contributed towards the development of BIOT as an ‘observatory for undisturbed ecosystems’.