The mangrove-dominated Ganges Delta – the Sundarbans – is a complex ecosystem comprising one of the three largest single tracts of mangrove forests in the world. The larger part is situated in Bangladesh, and a smaller portion of it lies in India. The Indian part of the forest is estimated to be about 40 per cent, while the Bangladeshi part is 60 per cent. To the south the forest meets the Bay of Bengal; to the east, it is bordered by the Baleswar River and to the north, there is a sharp interface with intensively cultivated land. The natural drainage in the upstream areas, other than the main river channels, is everywhere impeded by extensive embankments and polders.

The Sundarbans was originally measured (about 200 years ago) to be of about 16,700 square kilometres (6,400 sq mi). Now it has dwindled into about one-third of its original size. The total land area today is 4,143 square kilometres (1,600 sq mi), including exposed sandbars with a total area of 42 square kilometres (16 sq mi); the remaining water area of 1,874 square kilometres (724 sq mi) encompasses rivers, small streams and canals. Rivers in the Sundarbans are meeting places of salt water and freshwater. Thus, it is a region of transition between the freshwater of the rivers originating from the Ganges and the saline water of the Bay of Bengal. The Sundarbans’ floor varies from 0.9 to 2.11 metres (3.0 to 6.9 ft) above sea level.

The Indian (West Bengal ) part of Sunderbans forest lies under the district of South & North 24 Parganas and comprises two parts :

1) Sundarban National Park:

Main article: Sundarbans National Park
The Sundarban National Park is a National Park, Tiger Reserve, and a Biosphere Reserve in West Bengal, India. It is part of the Sundarbans on the Ganges Delta, and adjacent to the Sundarbans Reserve Forest in Bangladesh. The delta is densely covered by mangrove forests and is one of the largest reserves for the Bengal tiger. It is also home to a variety of bird, reptile and invertebrate species, including the salt-water crocodile. The present Sundarbans National Park was declared as the core area of Sundarbans Tiger Reserve in 1973 and a wildlife sanctuary in 1977. On 4 May 1984, it was declared a National Park.

2) Sajnakhali Wildlife Sanctuary:

Sajnakhali Wildlife Sanctuary is a 362-square-kilometre area in the northern part of the Sundarbans delta in South 24 Parganas district, West Bengal, India. It is mainly mangrove scrub, forest and swamp. It was set up as a sanctuary in 1976. It is home to a rich population of different species of wildlife, such as waterfowl, heron, pelican, spotted deer, rhesus macaques, wild boar, tigers, water monitor lizards, fishing cats, otters, olive ridley turtles, crocodiles, batagur terrapins, and migratory birds.

Biotic factors here play a significant role in physical coastal evolution, and for wildlife, a variety of habitats have developed which include beaches, estuaries, permanent and semi-permanent swamps, tidal flats, tidal creeks, coastal dunes, back dunes and levees. Sundarbans features two ecoregions — “Sundarbans freshwater swamp forests” (IM0162) and “Sundarbans mangroves” (IM1406).

1) Sundarbans freshwater swamp forests:

The Sundarbans freshwater swamp forests are a tropical moist broadleaf forest ecoregion. It represents the brackish swamp forests that lie behind the Sundarbans Mangroves, where the salinity is more pronounced. The freshwater ecoregion is an area where the water is only slightly brackish and becomes quite fresh during the rainy season when the freshwater plumes from the Ganges and the Brahmaputra rivers push the intruding salt water out and bring a deposit of silt. The Sundarbans freshwater swamp forests lie between the upland Lower Gangetic plains moist deciduous forests and the brackish-water Sundarbans mangroves bordering the Bay of Bengal.

2) Sundarbans Mangroves:

The Sundarbans Mangroves ecoregion on the coast forms the seaward fringe of the delta and is the world’s largest mangrove ecosystem. The dominant mangrove species Heritiera fomes is locally known as sundry or Sundari. Mangrove forests are not home to a great variety of plants. They have a thick canopy, and the undergrowth is mostly the seedlings of the mangrove trees. Twenty-six of the fifty broad mangrove species found in the world grow well in the Sundarbans.

The Sundarbans flora is characterised by the abundance of Sundari (Heritiera fomes), gewa (Excoecaria agallocha), goran (Ceriops decandra) and keora (Sonneratia apetala) all of which occur prominently throughout the area. The characteristic tree of the forest is the sundari (Heritiera littoralis), from which the name of the forest had probably been derived. It yields a hard wood, used for building houses and making boats, furniture and other things. New forest accretions is often conspicuously dominated by keora (Sonneratia apetala) and tidal forests. It is an indicator species for newly accreted mudbanks and It is an indicator species for newly accreted mudbanks and is an important species for wildlife, especially spotted deer (Axis axis). There is abundance of dhundul or passur (Xylocarpus granatum) and kankra (Bruguiera gymnorhiza) though distribution is discontinuous. Among palms, Poresia coaractata, Myriostachya wightiana and golpata (Nypa fruticans), and among grasses spear grass (Imperata cylindrica) and khagra (Phragmites karka) are well distributed.

The varieties of the forests that exist in Sundarbans include mangrove scrub, littoral forest, saltwater mixed forest, brackish water mixed forest and swamp forest. Besides the forest, there are extensive areas of brackish water and freshwater marshes, intertidal mudflats, sandflats, sand dunes with typical dune vegetation, open grassland on sandy soils and raised areas supporting a variety of terrestrial shrubs and trees.

Fauna:

The Sundarbans provides a unique ecosystem and a rich wildlife habitat. According to the 2021 tiger census, the Sundarbans have about 96 tigers in India . Earlier estimates, based on counting unique pugmarks, were much higher. The more recent counts have used camera traps, an improved methodology that yields more accurate results.

A study has revealed that the Indian part of the Sundarbans supports diverse biological resources including at least 150 species of commercially important fish, 270 species of birds, 42 species of mammals, 35 reptiles and 8 amphibian species, although new ones are being discovered. The Sundarbans is an important wintering area for migrant water birds and is an area suitable for watching and studying avifauna.

Mammals:

The Sundarbans are an important habitat for the Bengal tiger (Panthera tigris). The forest also provides habitat for small wild cats such as the jungle cat (Felis chaus), fishing cat (Prionailurus viverrinus), and leopard cat (P. bengalensis).

Several predators dwell in the labyrinth of channels, branches, and roots that poke up into the air. This is the only mangrove ecoregion that harbors the Indo-Pacific region’s largest terrestrial predator, the Bengal tiger. Unlike in other habitats, tigers live here and swim among the mangrove islands, where they hunt scarce prey such as the chital deer (Axis axis), Indian muntjacs (Muntiacus muntjak), wild boar (Sus scrofa), and Rhesus macaque (Macaca mulatta).

Avifauna:

The forest is also rich in bird life, with 286 species including the endemic brown-winged kingfishers (Pelargopsis amauroptera) and the globally threatened lesser adjutants (Leptoptilos javanicus) and masked finfoots (Heliopais personata) and birds of prey such as the ospreys (Pandion haliaetus), white-bellied sea eagles (Haliaeetus leucogaster) and grey-headed fish eagles (Ichthyophaga ichthyaetus). Some more popular birds found in this region are open billed storks, black-headed ibis, water hens, coots, pheasant-tailed jacanas, pariah kites, brahminy kites, marsh harriers, swamp partridges, red junglefowls, spotted doves, common mynahs, jungle crows, jungle babblers, cotton teals, herring gulls, Caspian terns, gray herons, brahminy ducks, spot-billed pelicans, great egrets, night herons, common snipes, wood sandpipers, green pigeons, rose-ringed parakeets, paradise flycatchers, cormorants, seagulls, common kingfishers, peregrine falcons, woodpeckers, Eurasian whimbrels, black-tailed godwits, little stints, eastern knots, curlews, golden plovers, pintails, white-eyed pochards and lesser whistling ducks.

Aquafauna

The Sundarbans National Park is home to olive ridley turtle, hawksbill turtle, green turtle, sea snake, dog-faced water snake, saltwater crocodile, South Asian river dolphin, king cobra, Russell’s viper, house gecko, monitor lizard, common krait, checkered keelback and rat snake, river terrapin, Indian flapshell turtle (Lissemys punctata), Indian peacock softshell turtle (Trionyx hurum), Asian water monitor (Varanus salvator), and Indian python. Fish and amphibians in the Sundarbans include sawfish, butter fish, electric ray, common carp, silver carp, barb, river eels, starfish, king crab, fiddler crab, hermit crab, prawn, shrimps, skipper frogs, common toads and tree frogs. One particularly interesting fish is the mudskipper, a gobioid that climbs out of the water into mudflats and even climbs trees.

Forest inventories reveal a decline in standing volume of the two main commercial mangrove species – sundari (Heritiera spp.) and gewa (Excoecaria agallocha) — by 40% and 45% respectively between 1959 and 1983. Therete a total ban on all killing or capture of wildlife other than fish and some invertebrates, it appears that there is a consistent pattern of depleted biodiversity or loss of species (notably at least six mammals and one important reptile) in the 20th century, and that the “ecological quality of the original mangrove forest is declining”.

The endangered species that live within the Sundarbans and extinct species that used to be include the Bengal tiger, estuarine crocodile, northern river terrapin (Batagur baska), olive ridley sea turtle, Gangetic dolphin, ground turtles, hawksbill sea turtles and king crabs (horse shoe). Some species such as hog deer (Axis porcinus), water buffalos (Bubalus bubalis), barasingha or swamp deer (Cervus duvauceli), Javan rhinoceros (Rhinoceros sondaicus), Indian rhinoceros (Rhinoceros unicornis) and the mugger crocodile (Crocodylus palustris) started to become extinct in the Sundarbans towards the middle of the 20th century, because of extensive poaching and hunting by the British and locals. There are other threatened mammal species, such as the capped langur (Semnopithecus pileatus), smooth-coated otter (Lutrogale perspicillata), Asian small-clawed otter (Aonyx cinerea) and large Indian civet (Viverra zibetha).

The unique and amazing Sundarbans National Park is known for being the largest Mangrove forest and natural home to the most dangerous and endangered predator in the wilderness of the dense forest, the Royal Bengal Tigers along with a large array of wild species of various flora and fauna. The estuarine of the Sundarbans makes it a unique and a must visit wildlife destination in India for the wildlife lovers as well as Nature lovers. Visiting the Sundarbans National Park is as easy as visiting any other tourism destination in India.

There are trains to Canning from Sealdah at regular intervals and the train covers this distance in one and a half hour. The private taxi or the shared vans are also available at Canning and takes you to Godhkhali Jetty, the initial point of the boat cruise to the Sundarbans.

The tourism department of West Bengal has well maintained the roadways and waterways connecting the Sundarbans National park to the nearest towns. The Sundarbans forest can be explored only through the medium of water transport so from the Godkhali port you can use the small or the big boat to further explore the wildlife of the Sundarbans.

Tourists from all over the world visit this forest not only to enjoy the sighting of the wild animals but also the gorgeous scenic view of the tranquil delta land. The forest can be explored through the water transports that sail in various river channels that divide the land into the deltas. However, the park is open throughout the year for the Safari, but if you know the best time to visit Sundarbans National Park then you can plan your tour accordingly to make your visit more enjoyable and interesting.

The days between the months of October and March are considered as the best time to visit the Sundarbans National Park as the weather during these days is more pleasant than any other time of the year. The winter season is the best time not only for a comfortable day trip in the dense forest but also for the better wildlife animals sighting as they come out from the dense forest and bask in the sun on the river banks. You can enjoy the boat safari in this pleasant weather and can also enjoy the various local foods that you will get while on the boat during your day safari.