Size
About 10,000 sq km — roughly 40% in India, the rest in Bangladesh.
Its tigers
The largest single tiger population anywhere in the world.
Its status
UNESCO World Heritage Site, and India’s largest Ramsar wetland.
Its threat
Rising sea levels and cyclones — West Bengal’s most eroded coastline.
- The World’s Largest Mangrove Forest
- Protected on Paper and in Practice
- Tigers That Swim
- More Than Just Tigers
- One of the Original Nine
- A Palm That Pays the Bills
- When the Forest Hunts Back
- A Myth About Why They Attack
- A Goddess for the Forest’s Edge
- A Forest Losing Ground, One Storm at a Time
- The Real Exam Trap on This Topic
- A Record Tiger Count Across the Border (2026)
The Basics
The World’s Largest Mangrove Forest
- What it is: the world’s largest mangrove forest, spread across the Ganga-Brahmaputra-Meghna delta on the Bay of Bengal.
- The split: covers about 10,000 square kilometres. Roughly 40% lies in India, mostly in West Bengal, and the rest in Bangladesh.
- The coastline: stretches about 260 kilometres, from the Hugli river estuary in India to the Meghna estuary in Bangladesh. It’s a single, unbroken belt of mangrove.
True or False: The Sundarbans is the world’s largest mangrove forest.
Its Protected Status
Protected on Paper and in Practice
- Recognition: a UNESCO World Heritage Site. Since January 2019, it’s also India’s largest Ramsar wetland site by area.
- The tigers: home to the single largest population of tigers found anywhere in the world, split across both the Indian and Bangladeshi halves.
- Two listings, not one: despite being one continuous ecosystem, UNESCO lists the Indian and Bangladeshi Sundarbans separately. India’s was listed in 1987, Bangladesh’s in 1997.
- A third layer: India also separately declared its own Sundarban Biosphere Reserve in 1989. It later gained UNESCO’s separate Man and Biosphere recognition in 2001.
Think it through. Why does UNESCO list the Indian and Bangladeshi Sundarbans as two separate World Heritage Sites, when they’re one continuous forest?
Show the explanation
UNESCO designations are nominated and managed by national governments, not by ecosystems. India and Bangladesh each nominated their own portion separately, under their own laws and agencies. The paperwork follows the international border. The mangroves, tides, and tigers on the ground don’t recognise it at all.
Its Name and Its Tigers
Tigers That Swim
- The name: “Sundarbans” comes from the sundari tree, the forest’s single most common mangrove species. Add “ban,” meaning forest, and you get “forest of sundari.”
- An amphibious life: Sundarbans tigers have adapted to an almost amphibious life. They can swim long distances between islands, and hunt fish, crabs, and water monitor lizards.
Think it through. Why would tigers here evolve to swim long distances, when tigers elsewhere don’t need to?
Show the explanation
The Sundarbans isn’t solid land. It’s hundreds of small islands, cut apart by tidal creeks that reshape with every tide. A tiger that can’t swim would be trapped on one tiny island. It couldn’t follow prey, find a mate, or escape a flooding storm surge. Swimming isn’t a quirk here — it’s a basic requirement for surviving this landscape.
More Than Just Tigers
More Than Just Tigers
- Other wildlife: besides the Royal Bengal Tiger, the forest shelters Ganges and Irrawaddy dolphins, plus estuarine crocodiles and the critically endangered river terrapin.
- Sheer diversity: researchers have recorded roughly 1,586 animal species and 81 distinct plant species across the whole region. That’s an unusually high count for one mangrove ecosystem.
- The terrain: an intricate network of tidal waterways cuts through the forest’s small, low-lying islands and mudflats, reshaping the coastline with every tide.
True or False: The Sundarbans hosts wildlife well beyond tigers, including dolphins, crocodiles, and a critically endangered terrapin.
One of the Original Nine
One of the Original Nine
- Sundarban Tiger Reserve: one of the nine original reserves set up when Project Tiger launched in 1973. Corbett, Kanha, Manas, and Ranthambore were the others.
- Still standing: Project Tiger has since grown from those 9 to 55 reserves, across 18 states. Sundarban remains one of its founding sites.
A Palm That Pays the Bills
A Palm That Pays the Bills
- Golpata: the nipa palm, locally called golpata, is a low mangrove palm. It’s harvested here for roof thatching and durable building material.
- Sap into sugar: its sugary sap is boiled down into jaggery and syrup. Roughly 50,000 people across the wider Sundarbans depend on this single plant for their livelihood.
- A working ecosystem: its rhizomes even help fishing nets float. Its roots help stabilise soil against the same erosion and storm surge covered later in this article.
The Real Exam Trap on This Topic
- The trap: exams describe a mix of mangrove, evergreen, and deciduous forest. They expect you to name the Sundarbans, betting on its mangrove fame.
- The real test: the Sundarbans is overwhelmingly mangrove alone. That three-forest-type combination actually belongs to the Andaman and Nicobar Islands.
- How to prepare: anchor Sundarbans to “pure mangrove delta,” and Andaman to “mangrove plus evergreen plus deciduous.” This swap stops working.
- UPSC CSP 2015 Asked which Indian region combines mangrove, evergreen, and deciduous forest together. Answer: the Andaman and Nicobar Islands, not South-West Bengal — they carry all three forest types in distinct zones across the island chain. View UPSC CSP 2015 GS Paper I, Q38 →
- CDS-I 2018 Asked which of four national parks, including Sundarbans National Park, are UNESCO World Heritage Sites. Answer: Keoladeo, Sundarbans, and Kaziranga all made the list. Ranthambore, despite its fame, did not. View CDS-I 2018 GK Paper, Q46 →
- UPSC CSP 2015 Asked which species holds the title of India’s national aquatic animal. Answer: the Gangetic (Ganges River) dolphin, declared in 2009 — one of the two dolphin species listed in this article’s Good to Know section. View UPSC CSP 2015 GS Paper I, Q25 →
Man-Eaters and a Drowning Forest
When the Forest Hunts Back
- Man-eaters: every year, honey collectors entering the forest are killed by Sundarbans tigers that have turned to hunting people.
- A drowning forest: sea-level rise is pushing more salt water into the mangroves, while upstream dams cut the freshwater flow the forest needs.
- Losing the sundari: rising salinity is killing off high-value trees like the sundari, the very species that gave the Sundarbans its name. The forest sits only about 2 metres above sea level on average.
A Discredited Theory
A Myth About Why They Attack
- The old theory: for decades, researchers blamed man-eating on salt water itself. The guess: drinking it damaged tigers’ kidneys and changed their temperament.
- Why it’s discredited: no dead or rescued Sundarbans tiger has ever shown the kidney damage that theory predicted. Most experts have since dropped it.
- The real explanation: low prey density and difficult terrain are the bigger factors. A relatively large number of people entering the forest makes humans an easy, opportunistic target.
Think it through. If the “salty water damages kidneys” theory was wrong, why did it take so long for researchers to drop it?
Show the explanation
It sounded scientifically plausible. It offered a tidy single cause for a frightening phenomenon. Testing it properly meant examining dead or rescued tigers — rare, difficult opportunities to come by. Without an easy way to disprove it quickly, a plausible-sounding but unverified theory can circulate for years. It took enough contrary evidence — healthy kidneys in every tiger actually examined — to finally overturn it.
True or False: Scientists have confirmed that drinking salt water damages Sundarbans tigers’ kidneys, causing them to attack humans.
Bonbibi
A Goddess for the Forest’s Edge
- Bonbibi: honey collectors and woodcutters entering the forest invoke Bonbibi, a guardian forest spirit. Both Hindu and Muslim communities here worship her.
- The legend: in local folklore, Bonbibi struck a truce with a tiger-demon king. The deal divided the forest, so people and tigers each had their own half.
- Why it persists: the tradition traces back centuries. It’s a direct response to just how real and constant the danger from this forest’s tigers has always been.
- Shared across faiths: both Hindu and Muslim communities worship the same forest guardian. That’s itself notable, in a region shaped by centuries of shared, hard-won survival.
Erosion and Cyclones
A Forest Losing Ground, One Storm at a Time
- Erosion: between 1990 and 2016, West Bengal lost more of its coastline to erosion than any other Indian state. That’s 63% of its shoreline, and 99 sq km of land — most of it in and around this delta.
- “Cyclone Capital”: India’s Meteorological Department has called the Sundarbans the country’s “Cyclone Capital,” hit by five severe cyclones between 2019 and 2021 alone.
- Amphan: Cyclone Amphan, in May 2020, was the strongest storm the Bay of Bengal had seen in 283 years. It severely damaged nearly a third of the delta, uprooting mangroves and flooding villages alike.
Think it through. Why does the Sundarbans get hit by so many severe cyclones compared to other parts of India’s coastline?
Show the explanation
The Bay of Bengal’s warm, shallow waters are unusually good at fuelling cyclones. The Sundarbans sits directly in the funnel-shaped northern end of that bay, where storms naturally converge as they track north. The delta’s islands are flat and low-lying too, just 2 metres above sea level on average. Nothing slows a storm surge down once it arrives.
A Record Tiger Count Across the Border (2026)
A Record Tiger Count Across the Border (2026)
- The announcement: on World Forest Day, 21 March 2026, Bangladesh’s Forest Department announced the final results of its 2024-25 tiger census. The count: 205 tigers, the highest ever recorded in the Bangladesh Sundarbans. (Source: Prothom Alo)
- Why the rise: officials credit two things — better patrolling, and a healthier prey base of deer and wild boar. (Source: Prothom Alo)
- Why it matters here: these are the same swimming, sometimes man-eating tigers described earlier in this article. They were just counted on the Bangladesh side of one shared forest.
Quick Q&A
Q: Why do Sundarbans tigers need to swim, unlike most tigers?
A: The forest is hundreds of small islands cut by tidal creeks — swimming is the only way to reach prey, mates, or escape rising water.
Q: What forest type combination is often confused with the Sundarbans on exams?
A: Mangrove + evergreen + deciduous together — that’s actually the Andaman and Nicobar Islands, not the Sundarbans, which is pure mangrove.
Q: Why is the sundari tree disappearing from the forest that’s named after it?
A: Rising salinity from sea-level rise and reduced upstream freshwater is killing off high-value trees like the sundari.
Q: What plant supports roughly 50,000 livelihoods in the Sundarbans?
A: Golpata, the nipa palm — used for roof thatching, and its sap boiled into jaggery and syrup.
✅ Test Yourself
Question 1 of 1
Leave a Reply