Great Nicobar is dominated by the Great Nicobar Biosphere Reserve. Constituted under the Man and Biosphere program of the Government of India, it includes Campbell Bay National Park and Galathea National Park. It spreads over an area of 885 sq km. This reserve is known for its unique bio-diversity and houses rich genetic germplasm resources.
The Great Nicobar represents the tropical rain forests in Andaman and Nicobar Islands biogeographic region. The major forest area in this Biosphere Reserve is still in its virgin state and rich in species composition. Unique fauna of this Biosphere Reserve include Crab eating Macaque(Macaca fascicularis), Salt water crocodile(Crocodylus porosus), Giant leather back turtle (Dermochelys coriacea), Malayan box turtle, Nicobar tree shrew, Nicobar Megapode, Reticulated python and the Giant Robber Crab(Birgus lactro). Other important species include Andaman wild pig, palm civet, fruit bat, Nicobar pigeon, white bellied sea Eagle, Nicobar serpent eagle, parakeets, water monitor lizard and many others.