World Heritage Identification Number: 798
World Heritage since: 1997
Category: Natural Heritage
WHE Type: Protected Areas & National Parks
Transboundary Heritage: No
Endangered Heritage: No
Country: 🇧🇩 Bangladesh
Continent: Asia
UNESCO World Region: Asia and the Pacific
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The Sundarbans: A Unique Mangrove Forest Ecosystem in South Asia
The Sundarbans, located in southwestern Bangladesh along the Bay of Bengal, forms part of the world's largest contiguous mangrove forest, extending across both Bangladesh and India. Covering approximately 10,000 square kilometers of land and water, the wider Sundarbans represents an ecosystem of global ecological significance. In 1997, a 1,395-square-kilometer property within the Bangladeshi Sundarbans was inscribed on the UNESCO World Heritage List as a natural site.
This World Heritage property is distinct from Sundarbans National Park in the Indian state of West Bengal, which received World Heritage status a decade earlier, in 1987, and covers approximately 1,330 square kilometers. Etymologically, the Sundarbans derives its name from the Sundari tree (Heritiera fomes), a characteristic and prominent mangrove species found throughout the region.
The forest is interspersed with a labyrinthine network of tidal waterways, mudflats, and small islands, creating a distinctive landscape shaped by river flows, tidal movements, and sediment deposition. These constantly changing environmental conditions support an extraordinary diversity of plant and animal life, making the region one of the world's most unique coastal environments.
The Sundarbans is a biodiversity hotspot, hosting hundreds of bird species, including the threatened Masked Finfoot and the Pied Kingfisher. The region is also renowned for its large predators, most notably the Royal Bengal tiger, which has adapted remarkably well to the dense mangrove vegetation and challenging tidal conditions. Other notable inhabitants include the estuarine crocodile, the Indian python and several species of dolphins. The combination of terrestrial, freshwater and brackish-water habitats supports an intricate food web and provides refuge for numerous threatened species.
The World Heritage site is not only rich in wildlife but also plays a crucial role in maintaining regional ecological balance. Its mangrove forests act as a natural buffer against cyclones and storm surges by reducing wave energy and helping stabilize shorelines. The forests also trap sediments and retain nutrients, supporting productive aquatic habitats and providing important nursery grounds for fish, shrimp and crabs. In addition, mangrove vegetation and its underlying soils store substantial quantities of carbon, contributing to climate regulation and the conservation of coastal biodiversity.
The Sundarbans is a remarkable example of dynamic ecological processes involving monsoon rainfall, flooding, delta formation, tidal influence and plant colonization. The landscape is constantly evolving as rivers and tides erode some areas while depositing sediments in others. New landforms may emerge, while existing islands change shape over time. These ongoing transformations make the region an important natural laboratory for scientists studying delta formation, coastal processes and mangrove ecosystem dynamics.
In terms of human use, the Sundarbans provides essential resources and livelihoods for surrounding communities, including fish, honey, wax and other forest products collected under applicable regulations. However, illegal resource extraction, overexploitation, pollution and habitat degradation pose significant threats to this fragile ecosystem. Climate change, rising sea levels, changing salinity and extreme weather events add further pressure.
Conservation efforts rely on protected-area management, scientific monitoring, habitat protection and community-based initiatives. In Bangladesh, these efforts include the management of protected areas within the forest, while cooperation with neighboring India is important for addressing environmental challenges affecting the wider ecosystem.
Altogether, the Sundarbans is a unique and vital mangrove forest ecosystem. Its rich biodiversity, ecological functions and cultural significance make it a natural heritage of global importance. Its UNESCO World Heritage recognition highlights the importance of protecting its habitats and the ecological processes that sustain them. As climate change and other environmental pressures increasingly affect coastal regions worldwide, continued conservation, responsible tourism and sustainable resource management will be essential to preserving this remarkable ecosystem for future generations.
UNESCO Description of the World Heritage Site
The Sundarbans mangrove forest, one of the largest such forests in the world (140,000 ha), lies on the delta of the Ganges, Brahmaputra and Meghna rivers on the Bay of Bengal. It is adjacent to the border of India’s Sundarbans World Heritage site inscribed in 1987. The site is intersected by a complex network of tidal waterways, mudflats and small islands of salt-tolerant mangrove forests, and presents an excellent example of ongoing ecological processes. The area is known for its wide range of fauna, including 260 bird species, the Bengal tiger and other threatened species such as the estuarine crocodile and the Indian python.
UNESCO Justification of the World Heritage Site
Criterion (ix): The Sundarbans provides a significant example of on-going ecological processes as it represents the process of delta formation and the subsequent colonization of the newly formed deltaic islands and associated mangrove communities. These processes include monsoon rains, flooding, delta formation, tidal influence and plant colonization. As part of the world’s largest delta, formed from sediments deposited by three great rivers; the Ganges, Brahmaputra and Meghna, and covering the Bengal Basin, the land has been moulded by tidal action, resulting in a distinctive physiology.
Criterion (x): One of the largest remaining areas of mangroves in the world, the Sundarbans supports an exceptional level of biodiversity in both the terrestrial and marine environments, including significant populations of globally endangered cat species, such as the Royal Bengal Tiger. Population censuses of Royal Bengal Tigers estimate a population of between 400 to 450 individuals, a higher density than any other population of tigers in the world. The property is the only remaining habitat in the lower Bengal Basin for a wide variety of faunal species. Its exceptional biodiversity is expressed in a wide range of flora; 334 plant species belonging to 245 genera and 75 families, 165 algae and 13 orchid species. It is also rich in fauna with 693 species of wildlife which includes; 49 mammals, 59 reptiles, 8 amphibians, 210 white fishes, 24 shrimps, 14 crabs and 43 mollusks species. The varied and colourful bird-life found along the waterways of the property is one of its greatest attractions, including 315 species of waterfowl, raptors and forest birds including nine species of kingfisher and the magnificent white-bellied sea eagle.
Encyclopedia Record: Sundarbans
Sundarbans is a mangrove forest area in the Ganges Delta formed by the confluence of the Ganges, Brahmaputra and Meghna Rivers in the Bay of Bengal. It spans the area from the Hooghly River in India's state of West Bengal to the Baleswar River in Bangladesh's Khulna Division. It comprises closed and open mangrove forests, land used for agricultural purpose, mudflats and barren land, and is intersected by multiple tidal streams and channels. Spread across 10,277 km2 (3,968 sq mi), it is the world's largest mangrove forest. It covers over 6,017 km2 (2,323 sq mi) in Bangladesh's Khulna Division. In West Bengal's Presidency division, they extend over 4,260 km2 (1,640 sq mi) in the South 24 Parganas and North 24 Parganas districts. Four protected areas in the Sundarbans are enlisted as UNESCO World Heritage Sites, viz. Sundarbans West, Sundarbans South, Sundarbans East in Bangladesh and Sundarbans National Park in India. The Indian Sundarbans were considered endangered in a 2020 assessment under the IUCN Red List of Ecosystems framework. The most abundant tree species are sundri and gewa. The forests provide habitat to 453 fauna wildlife, including 290 bird, 120 fish, 42 mammal, 35 reptile and eight amphibian species. Despite a total ban on all killing or capture of wildlife other than fish and some invertebrates, there has been a consistent pattern of depleted biodiversity or loss of species in the 20th century, with the ecological quality of the forest declining.Additional Site Details
Area: 139,500 hectares
Number of Components: 3
(x) — Contains most important habitats for biodiversity
Coordinates: 21.95 , 89.18333
IUCN World Heritage Outlook
The 2025 Conservation Outlook on The Sundarbans reports the following assessment:
Source: International Union for Conservation of Nature (IUCN) · View assessment
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© Monster eagle, CC BY-SA 3.0 Resized from original. (This derivative is under the same CC BY-SA license.)
World Heritage Research
Discover scientific research and academic studies that deepen our understanding of The Sundarbans from its history and significance to its conservation, management, and contemporary challenges.
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Turning Brackish: Salinity-Driven Mangrove and Fisheries Decline in the Bangladesh Sundarbans.
Reduced freshwater inflow from the Ganges, driven by upstream abstraction and regulation, has intensified salinity intrusion into the Bangladesh Sundarbans, threatening its biodiversity and livelihoods. This study quantifies how salinity exceeds physiological tolerance thresholds for high-value mangrove species like Heritiera fomes (Sundri), causing a 40% decline in suitable habitat while salt-tolerant but lower-value Excoecaria agallocha expands. Analysis of hydrological records, forest cover data, and fisheries statistics from 1996 to 2016 reveals a 54% drop in fish species richness at Mongla market and accelerating ecosystem degradation. Climate projections to 2050 confirm irreversible losses under current trends unless institutional reforms address Ganges water-sharing. The findings underscore the critical need for upstream freshwater management to sustain biodiversity and the livelihoods of 2.7 million dependent communities.
Imtiaz, A., Irfan Sakib, B., & Faria, A. (2026). Turning Brackish: Salinity-Driven Mangrove and Fisheries Decline in the Bangladesh Sundarbans. Zenodo. https://doi.org/10.5281/ZENODO.20089071
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The Relentless Tide of History
Historical analysis reveals that the Sundarbans, initially perceived as a hostile environment by colonial powers, transitioned into a structured conservation and forest administration system between 1862 and 1943. The study highlights how land leases for agriculture and timber extraction were formalized during this period, culminating in the designation of the entire area as a reserved forest. This transformation underscores the intersection of colonial governance and environmental management, providing insights into the early stages of conservation efforts in one of the world's most significant mangrove ecosystems.
Deb, N. (2025). The Relentless Tide of History. Niranjan Mondal’s A Tale of High and Low Tides, 131–147. https://doi.org/10.4324/9781003626602-5
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Functional composition outweighs taxonomic and functional diversity in maintaining ecosystem properties and processes of mangrove forests
A study on the Sundarbans mangrove forests reveals that functional composition (FC) of leaf area plays a more significant role in maintaining ecosystem properties and processes (MEPP) than species richness or functional diversity. This finding suggests that regionally dominant species with high leaf area and nitrogen content, along with functionally diverse species, are crucial for sustaining mangrove ecosystems as climate change mitigation solutions. Researchers analyzed data from 93 plots across the Sundarbans Reserved Forests in Bangladesh, examining forest inventory, plant traits, and environmental factors. They found that FC positively influenced total biomass, productivity, sediment organic carbon, and nutrient contents, while also mediating the negative impact of sediment salinity on MEPP. The study highlights the importance of prioritizing specific species in conservation efforts to support mangrove ecosystem services.
Rahman, M. M., Zimmer, M., Donato, D., Ahmed, I., Xu, M., & Wu, J. (2024). Functional composition outweighs taxonomic and functional diversity in maintaining ecosystem properties and processes of mangrove forests. Global Change Biology, 30(1). Portico. https://doi.org/10.1111/gcb.17152
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Climate change, multi-hazards and society: An empirical study on the coastal community of Indian Sundarban
A significant disparity exists in the coping strategies employed by coastal communities in the Indian Sundarbans to mitigate climate change-related multi-hazards. While island households utilize 4–6 adaptation techniques (78%), primarily asset-related, other regions rely on 1–3 methods (56%), often centered around food and finance safeguards. This variation underscores the differential impact of hazards across geographical locations. The study, based on a survey of 850 rural households in four distinct areas—islands, coastal, riverine, and inland—reveals that migration is also a notable tactic in the region. These findings highlight the urgent need for tailored mitigation and adaptation strategies to address the escalating threats posed by climate change in vulnerable coastal regions.
Mondal, M., Biswas, A., Haldar, S., Mandal, S., Mandal, P., Bhattacharya, S., & Paul, S. (2022). Climate change, multi-hazards and society: An empirical study on the coastal community of Indian Sundarban. Natural Hazards Research, 2(2), 84–96. https://doi.org/10.1016/j.nhres.2022.04.002
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Significant reduction of carbon stocks and changes of ecosystem service valuation of Indian Sundarban
Over the past four and a half decades, the Sundarbans mangrove ecosystem has experienced a significant decline in both carbon stocks and ecosystem service values (ESVs), with total losses amounting to 3310.79 million USD and 6.31 Tg of carbon, respectively. This deterioration is attributed to natural and anthropogenic pressures, including illegal human encroachment. The study utilized time-series satellite data (1975, 2000, and 2020) alongside the InVEST model to analyze dynamic patterns of carbon sequestration and employed the Getis-Ord Gi* method to identify ESV change hotspots. These findings underscore the urgent need for stricter regulatory measures to protect this critical ecosystem, which is vital for millions of people.
Bera, B., Bhattacharjee, S., Sengupta, N., Shit, P. K., Adhikary, P. P., Sengupta, D., & Saha, S. (2022). Significant reduction of carbon stocks and changes of ecosystem service valuation of Indian Sundarban. Scientific Reports, 12(1). https://doi.org/10.1038/s41598-022-11716-5
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Microplastics pollution load in Sundarban delta of Bay of Bengal
A significant microplastics pollution load, exceeding 56 tons immediately after Cyclone Amphan in 2020 and an estimated 4 million tonnes annually from rivers, threatens the Sundarban mangrove forest. This study highlights the severe ecological risks posed by microplastic contamination, including trophic transfer and bioaccumulation, which can degrade natural resources, disrupt livelihoods, and exacerbate poverty. While governments of India and Bangladesh have implemented mitigation policies, urgent joint initiatives are needed to address pollution risks, conserve biodiversity, and promote sustainable development in this UNESCO World Heritage Site.
Kumar, R., Sinha, R., Refat Jahan Rakib, Md., Padha, S., Ivy, N., Bhattacharya, S., Dhar, A., & Sharma, P. (2022). Microplastics pollution load in Sundarban delta of Bay of Bengal. Journal of Hazardous Materials Advances, 7, 100099. https://doi.org/10.1016/j.hazadv.2022.100099
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Livelihood, conflict and tourism: An assessment of livelihood impact in Sundarbans, West Bengal
A significant shift in livelihood patterns is occurring among communities residing near the Sundarbans, the world's largest mangrove forest reserve. This study reveals that while tourism is appreciated, unregulated and irresponsible tourist behavior poses a major threat to the ecosystem's flora and fauna. Additionally, rising water levels and increased salinity are submerging vast areas of the Sundarbans, exacerbating challenges such as tiger conservation and embankment erosion. The research employed primary surveys, secondary data collection, descriptive, and ethnographic methods to analyze community perceptions and livelihood impacts. It underscores the urgent need for a region-specific approach and regional planning to address these multifaceted threats effectively.
Jamal, S., Ghosh, A., Hazarika, R., & Sen, A. (2022). Livelihood, conflict and tourism: An assessment of livelihood impact in Sundarbans, West Bengal. International Journal of Geoheritage and Parks, 10(3), 383–399. https://doi.org/10.1016/j.ijgeop.2022.07.004
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