A Forest Born from Three Rivers
Where the Ganges, Brahmaputra, and Meghna rivers finally exhaust themselves into the Bay of Bengal, they leave behind one of the most complex and ecologically rich landscapes on earth. The Sundarbans, stretching across roughly 10,277 square kilometres of the Bengal delta, is the world’s largest contiguous mangrove forest. Bangladesh holds the larger share, around 6,017 square kilometres within Khulna Division, while the remaining portion falls within India’s West Bengal state across the South and North 24 Parganas districts.
The name itself carries a quiet poetry. In Bengali, “Sundarbans” (সুন্দরবন) translates simply as “beautiful forest.” Linguists and botanists both have a claim to the word’s origin: the most widely accepted explanation links it to the sundri tree (Heritiera fomes), the dominant mangrove species of the region, whose dense stands once carpeted the delta floor. A competing theory suggests the name derives from Samudraban, meaning “sea forest,” which is equally apt for a place where salt water and freshwater are in constant negotiation.
A Landscape Unlike Any Other
The Sundarbans is not simply a forest. It is a mosaic of closed and open mangrove stands, tidal mudflats, small islands, agricultural fringes, and an intricate web of waterways that makes almost every corner of the forest accessible by boat. Rivers here are not purely freshwater or purely saline; they are transitional, shifting with the tides, carrying sediment from the Himalayas and salt from the open ocean. The forest floor itself ranges from less than a metre to just over two metres above sea level, which means the entire ecosystem lives at the mercy of tidal cycles.
The interconnected network of channels, creeks, and rivers is the forest’s circulatory system. It distributes nutrients, moves wildlife, and has shaped the lives of the communities on the forest’s edge for centuries. The mangrove vegetation is not passive in this process; it actively traps sediment, builds new land, and stabilises coastlines. Without the Sundarbans, millions of people in and around Khulna, Mongla, and the broader coastal belt would be far more exposed to cyclone surges, tsunamis, and erosion.
History: From Mauryan Settlements to British Surveys
Human presence in the Sundarbans delta goes back at least to the Mauryan era, roughly the 4th to 2nd centuries BCE. Ruins of an abandoned city found in the Baghmara Forest Block have been attributed to Chand Sadagar, a semi-historical figure from Bengali folklore associated with the pre-Mauryan period. Archaeological work at Kapilmuni in Paikgacha Upazila, north of the forest, has uncovered evidence of urban settlement from the early medieval period, suggesting the delta supported organised communities long before colonial-era mapping.
During the Mughal period, forest tracts were leased to settlers by local rulers, and the delta’s agricultural potential drew people steadily inward. The shift toward formal administration came with the British. In 1757, the East India Company acquired proprietary rights over the Sundarbans from Mughal Emperor Alamgir II, and by 1764 had completed a systematic survey of the area. Formal forest management, however, took another century to arrive. The first Forest Management Division with jurisdiction over the Sundarbans was established in 1869. By 1875, large portions had been declared reserved forests under the Indian Forest Act of 1865, and a dedicated Forest Division was created in 1879, headquartered in what is now Khulna. The first formal management plan was drawn up for the period 1893 to 1898.
At its original measurement roughly 200 years ago, the Sundarbans covered approximately 16,700 square kilometres. Today, the total land area has shrunk to around 4,143 square kilometres, a reduction to roughly one-third of its historical extent, driven by agricultural conversion, settlement, and more recently by climate-related pressures.
Wildlife: Tigers, Birds, and a Fragile Abundance
The Sundarbans supports 453 recorded fauna species: 290 birds, 120 fish, 42 mammals, 35 reptiles, and eight amphibians. The Bengal tiger (Panthera tigris) is the forest’s most iconic resident and one of the primary reasons the Sundarbans draws researchers, conservationists, and visitors from around the world. The Sundarbans tiger population is notable for being the only tiger population in the world adapted to a tidal, saline mangrove environment. These tigers are known to swim between islands and have, over generations, developed behaviours distinct from their counterparts in drier forests.
Beyond the tiger, the forest shelters spotted deer (chital), saltwater crocodiles, Irrawaddy dolphins, fishing cats, and a remarkable diversity of migratory and resident birds. The two dominant tree species, sundri and gewa (Excoecaria agallocha), define the forest’s canopy and understorey, but the botanical diversity runs much deeper, with numerous mangrove species adapted to varying levels of salinity and tidal inundation.
UNESCO Recognition and Conservation Status
Four protected areas within the Sundarbans carry UNESCO World Heritage Site status. Three are on the Bangladesh side: Sundarbans West, Sundarbans South, and Sundarbans East. The fourth, Sundarbans National Park, lies in India. This dual-country recognition reflects the forest’s global ecological significance, though it has not insulated the ecosystem from ongoing degradation.
A 2020 assessment under the IUCN Red List of Ecosystems framework classified the Indian Sundarbans as endangered. The broader ecosystem faces a compounding set of pressures. Cyclone Sidr in 2007 damaged approximately 40 percent of the forest. Cyclone Aila in May 2009 caused massive casualties and affected at least 100,000 people. Rising sea levels driven by climate change are increasing salinity levels throughout the delta, stressing species that can only tolerate a narrow salinity range. Reduced freshwater inflow from upstream river systems compounds this problem. A 2016 UNESCO report raised serious concerns about the proposed Rampal coal-fired power station near the forest boundary, warning that its operation would further damage the ecosystem through thermal discharge, increased vessel traffic, and air and water pollution.
The Sundarbans Today: Between Wonder and Threat
For visitors, the Sundarbans remains one of the most extraordinary destinations in South Asia. Boat journeys through the tidal channels, guided forest walks, and the ever-present possibility of spotting a Bengal tiger in the wild draw travellers to the Khulna region each year. The Bangladesh Forest Department manages tourism through designated zones, and several eco-tourism lodges and government rest houses operate near Mongla and Morrelganj as entry points.
The communities living on the forest’s edge, the honey collectors known as mawalis, the fishermen, and the woodcutters, have maintained a relationship with the Sundarbans for generations that is both dependent and deeply respectful. Their knowledge of the forest’s rhythms, its tides, its dangers, and its seasonal gifts is a form of living heritage that formal conservation plans are increasingly trying to incorporate rather than exclude.
Experts studying the region consistently point to mangrove restoration, managed retreat from the most vulnerable coastal zones, and investment in resilient infrastructure as the most viable paths forward. The Sundarbans has survived millennia of storms, floods, and human pressure. Whether it can survive the accelerating pace of climate change and industrial encroachment in the decades ahead is the defining conservation question for Bangladesh’s natural heritage.
Image: Wikimedia Commons / Shihabur Rahman (CC BY-SA 4.0)