Sundarbans: The World’s Largest Mangrove Forest and Home of the Royal Bengal Tiger

Twice a day, the Bay of Bengal pushes salt water up hundreds of channels at the mouth of the Ganga and floods the forest floor of the Sundarbans. The trees survive by breathing through roots that poke up out of the mud like pencils. This is the largest tidal mangrove forest in the world, about ten thousand square kilometres split between India and Bangladesh, and it is also one of the few places where tigers routinely swim from island to island.

About forty percent of the forest lies in India, in the South and North 24 Parganas districts of West Bengal. The Indian Sundarbans National Park is a UNESCO World Heritage Site, inscribed in 1987. Millions of people also live on the drier islands at its edge, farming, fishing and collecting wild honey.

Where are the Sundarbans?

The Sundarbans sit on the delta formed by the Ganga, Brahmaputra and Meghna rivers where they meet the Bay of Bengal. The Indian part of the forest covers about 4,260 square kilometres, and the Bangladesh part is larger, at about 6,000 square kilometres. Together they make up the world’s largest single block of tidal halophytic (salt-tolerant) mangrove forest.

On the Indian side, the Sundarbans Tiger Reserve has a core area, the Sundarbans National Park, which visitors cannot enter, and a surrounding zone where regulated tourism is allowed. The reserve lies roughly 110 kilometres south-east of Kolkata.

How mangroves survive in salt water

Mangroves are trees adapted to salty, waterlogged soil. Because the mud holds almost no oxygen, many species send up breathing roots called pneumatophores, which stick out of the ground around the trunk. Several species also have seeds that germinate while still on the parent tree, so the seedling is ready to root as soon as it drops into the mud.

The Sundarbans has around eighty species of mangrove and related plants. The forest takes its name from the sundari tree (Heritiera fomes), once the dominant species. Rising salinity in the water now threatens the sundari in many parts of the delta, though other mangroves such as goran and gewa are still widespread.

The tide is what organises everything here. When it comes in, large stretches of the forest floor go under; when it goes out, the mud and the roots reappear. Fish, crabs, birds and the people who fish for them all plan their day around this cycle.

The Royal Bengal Tiger of the Sundarbans

The Sundarbans is best known for the Royal Bengal Tiger. Around a hundred tigers live in the Indian Sundarbans and roughly the same number across the border in Bangladesh. It is one of the most important tiger populations in the world, and the only one living in a mangrove forest.

These tigers behave differently from tigers in central India. They swim regularly, sometimes across wide channels between islands, and they will eat fish and crabs when deer and wild boar are scarce. They also attack people more often than tigers anywhere else, and over the last century hundreds of fishermen, crab collectors and honey gatherers have been killed.

Nobody is quite sure why. One theory blames the salty water the tigers drink; another points to the shrinking forest and competition for prey. A more practical explanation is that people here have to enter the tiger’s habitat every day to earn a living, often on foot or in small boats.

Bonbibi and the people of the delta

Around four million people live on the inhabited islands of the Indian Sundarbans. They grow rice on land that floods during storms, collect honey from the forest, fish in the channels and catch crabs and prawn seed.

Cyclones from the Bay of Bengal hit the delta often. Cyclone Aila in 2009 and Cyclone Amphan in 2020 flooded large parts of it with sea water, ruining fields for years afterwards. Fresh drinking water is scarce, and tiger attacks still claim lives.

People have adapted in practical ways. Houses stand on raised earth plinths, embankments ring the islands, and a family’s boat is usually its most valuable possession. Before entering the forest, fishermen and honey collectors pray to Bonbibi, the forest goddess who protects them from the tiger spirit Dokkhin Rai. She is worshipped by Hindus and Muslims alike, and her shrines appear in villages across the delta.

Other wildlife: crocodiles, dolphins and birds

Saltwater crocodiles live in the tidal creeks, and Indian pythons, king cobras and water monitor lizards live on the islands. The Ganges river dolphin, one of the few surviving species of river dolphin, is found in the channels nearer the freshwater end of the delta.

Several hundred bird species have been recorded, including winter migrants from Central Asia. Kingfishers (the area has several species), herons, white-bellied sea eagles and pelicans are common sights from a boat.

Below the water, the mangrove roots act as a nursery for fish, prawns and crabs. Many marine species spend their early life sheltered among the roots before moving out to the open sea, which is one reason coastal fisheries in the region rely on this forest.

How to visit the Sundarbans

The best time to visit is November to February, when the weather is cool and dry. Summer is hot and humid, and the monsoon months bring rough water and the risk of cyclones.

Roads end at the outer villages, so you see the forest from a boat. Most trips start in Kolkata with a drive of about three hours to the jetties at Sonakhali or Godkhali. From there a launch becomes your transport, and often your accommodation, for two or three days. Overnight tours are the usual way to visit; day trips are possible but cover much less.

A typical tour stops at Sajnekhali, the reserve’s main visitor centre, which has a watchtower and a small mangrove interpretation area. Boats then go on to the Sudhanyakhali and Dobanki watchtowers. Spotted deer, wild boar, monitor lizards and crocodiles are often seen, but a tiger sighting is a matter of luck, and many visitors go home without one.

The best wildlife viewing is in the early morning and late afternoon, when the boats move slowly along the narrower creeks. Entry permits are required, so book through the West Bengal Forest Department or an approved operator who can arrange them.

Threats to the Sundarbans

Rising sea levels are eroding the outer islands, and some islands in the Indian Sundarbans have already been abandoned. Salinity is increasing as less fresh water flows down from upstream, which is killing sundari trees. Severe cyclones are hitting the delta more often, and farming and fishing push steadily into the forest edge.

The West Bengal Forest Department, the central government and international conservation groups run programmes to protect what remains. These include nylon net fencing along village boundaries to keep tigers out, training for villagers on how to behave in tiger areas, and mangrove replanting on eroded mudbanks.

The mangroves also protect the people behind them. The forest breaks the force of storm surges, and it has helped shield Kolkata and the surrounding districts from the worst cyclones for centuries.

For a sense of what life on these islands is like before you go, read Amitav Ghosh’s The Hungry Tide. It is set on the islands near the tiger reserve and tells the Bonbibi story through the people who still pray to her.

Frequently Asked Questions

Is the Bangladesh Sundarbans also a World Heritage Site?

Yes. The Bangladesh Sundarbans was listed as a separate UNESCO World Heritage Site in 1997, ten years after the Indian national park. Both sides are also Ramsar wetlands of international importance.

Can you see a tiger in the Sundarbans?

It is possible but not likely on a short trip. The tigers are shy and the forest is dense, so most visitors see deer, crocodiles and birds instead.

Do you need a permit to visit the Sundarbans?

Yes. Entry into the tiger reserve needs a permit from the West Bengal Forest Department, which tour operators usually arrange as part of the package.

What does the name Sundarbans mean?

It is usually explained as “forest of sundari trees”, after the mangrove species that once dominated it. Another explanation reads it as “beautiful forest”, from the Bengali word sundar.