The Great Nicobar Biosphere Reserve lies in the Great Nicobar Island, which forms the southern end of the Archipelagic Nicobar Islands. Located in the Bay of Bengal, the Andaman and Nicobar islands became a union territory of the Republic of India in 1956. The Great Nicobar Biosphere Reserve, which stretches over an area of 1,03,870 hectares, got the UNESCO tag in 2013. The biosphere encompasses nearly 85% of the island of Great Nicobar and includes two National Parks - the larger Campbell Bay National Park in the north and Galathea National Park in the south. 

The Great Nicobar Biosphere is recognised as a terrestrial ecoregion for its rain forests and many endemic species. Its warm tropical climate with temperatures ranging between 22 to 30 degrees C and heavy rainfall during monsoons, helps in the growth of evergreen and deciduous tropical and subtropical moist broadleaf forests in the interiors and mangrove forests in the coastal areas. A wide range of ecosystems can be seen here ranging from mountain ranges, with the highest peak (Mt. Thullier) being at a height of 642 m above sea level, to coastal plains. Great Nicobar is the only island in the archipelago that has a significant amount of fresh surface water in terms of streams and rivers.

The biodiversity found in the Reserve’s flora and fauna is rich. It includes rare and indigenous species such as Cyathea albosetacea (tree fern) and Phalaenopsis speciosa (orchid). Besides these, there are several species of angiosperms, ferns, gymnosperms, bryophytes, and lichens, too. The Biosphere also has a large number of endemic and endangered species of fauna, including 11 species of mammals, 32 species of birds, 7 species of reptiles and 4 species of amphibians. The Crab-eating Macaque, Nicobar Tree Shrew, Dugong, Nicobar Megapode, Serpent Eagle, saltwater crocodile, marine turtles, and Reticulated Python are a few endangered species.

Great Nicobar is an inhabited island and the two main indigenous communities that live here are the Shompen (around 200 in number), and the Nicobarese (around 300 in number), both of Mongoloid origin. The Nicobarese call themselves Holchu, which means a “friend”. The members of the tribes who live inside the island depend on forest resources for their survival and are also horticulturists. The ones living on the coast mainly depend on fishing. These tribes suffered heavy losses during the 2004 tsunami and were relocated to other places on the island such as the Afra Bay on the North Coast and the area near the Campbell Bay.  

The native islanders avoided interaction with the outside world for a long time, but are now open to contact. However, this has led to issues such as the spread of diseases and pollution. Thus, declaring the area as a Biosphere Reserve will help in preserving the indigenous people, their languages, which include Austroasiatic languages and Nicobarese, and other facets of their socio-cultural traditions.  It will also lead to the implementation of management strategies that will preserve the terrestrial, marine, coastal and freshwater resources, and help devise strategies for sustainable development.