The entire Sunderban, covering some 10,000 sq. km of mangrove forest and water (of which some 40% is in India and the rest in Bangladesh), is part of the world's largest delta (80,000 sq. km) formed with the sediments deposited by three great rivers, the Ganges, Brahmaputra and Meghna, which converge on the Bengal Basin.
Intricate networks of interconnecting waterways, of which the larger channels are often a mile or more in width and run in a north-south direction, intersect the whole Sunderban area.
In the Indian Sunderban, the western portion receives some freshwater through the Hoogly-Bhagirathi river system but that portion designated, as the tiger reserve is essentially land-locked, its rivers having become almost completely cut off from the main freshwater sources over the last 600 years. Thus, waterways in the Tiger reserve are maintained largely by the diurnal tidal flow.

Of the 230 odd species found in the reserve some are :

Red Junglefowl, Lesser Whistling-duck, Cotton Pygmy-goose, Streak-throated Woodpecker, Common Flameback, Greater Flameback, Coppersmith Barbet, Brown-winged Kingfisher, Stork-billed Kingfisher, Black-capped Kingfisher, Collared Kingfisher, Pied Kingfisher, Green Bee-eater, Green-billed Malkoha, Greater Coucal, Eurasian Collared Dove, Orange-breasted Green Pigeon, Yellow-footed Green Pigeon, Grey-headed Lapwing, Pallas's Gull, Brown-headed Gull, Black-headed Gull, Whiskered Tern, Brahminy Kite, White-bellied Fish Eagle.

White-rumped Vulture, Little Egret, Goliath Heron, Little Heron, Black-crowned Night Heron, Yellow Bittern, Cinnamon Bittern, Asian Openbill, Lesser Adjutant, Ashy Woodswallow, Small Minivet, White-throated Fantail, Bronzed Drongo, Common Iora, Ashy Prinia, Oriental White-eye, Blyth's Reed Warbler, Clamorous Reed Warbler, Common Tailorbird, Greenish Warbler, Indian Scimitar Babbler, Chestnut-capped Babbler, Striated Babbler, Purple-rumped Sunbird, Purple Sunbird and Loten's Sunbird.

Nearest Railhead: Sealdah/Howrah (Kolkata)

Nearest Airport: Netaji Subhas International Airport, Kolkata.

Approx travelling time: Sonakhali (Basanti)-the jetty and also the last motorable point on the Kolkata-Basanti highway, is a two and half hours drive from Kolkata. The national park is three hours cruise from Sonakhali jetty.

Accommodation: We run Sunderban Jungle Camp at Bali Island opposite the Tiger Reserve. There are also few private hotels and resorts in Pakhiralay/Dayapur area. The West Bengal Tourism Development Corporation runs a lodge at Sajnakhali.