Wetlands are found on every continent except Antarctica, but they cluster in two main latitude bands: the boreal north (between 50°N and 70°N) and the tropics near the equator. These two zones hold the vast majority of the world’s wetland area. Beyond those hotspots, wetlands appear along coastlines, river floodplains, and lake margins on nearly every landmass, from the arid interior of Australia to the temperate river valleys of Europe.
The Two Major Wetland Belts
Satellite modeling and ground surveys show that global wetland area peaks sharply between 50°N and 70°N latitude, spanning the boreal forests and tundra of Canada, Scandinavia, and Russia. A second, smaller peak appears near the equator, driven by the massive river basins of South America, Central Africa, and Southeast Asia. Together, these two belts account for the largest continuous stretches of wetland on Earth.
The pattern makes sense when you consider what wetlands need: water that sticks around. In the far north, flat terrain, permafrost, and slow drainage keep the ground waterlogged for much of the year. In the tropics, heavy rainfall and enormous river systems flood vast lowlands on a seasonal or permanent basis.
Boreal and Arctic Wetlands
The single largest concentration of wetlands sits in Russia’s Western Siberian Lowlands. This region is the world’s largest high-latitude wetland, with a waterlogged forest and peatland zone spanning roughly 1.8 million square kilometers, about two-thirds of western Siberia. Over 900,000 square kilometers of that area is peatland, with an average peat depth of about 2.5 meters. In total size, it ranks second only to the Amazon Basin among the world’s largest wetlands.
Canada’s Hudson Bay Lowlands form the other major boreal wetland, stretching across northern Ontario and Manitoba. Much of this landscape is bog and fen, fed by snowmelt and underlain by permafrost. Scandinavia, particularly Finland and northern Sweden, adds another significant pocket of boreal peatland. These northern wetlands are enormous carbon stores. The Western Siberian peatlands alone hold an estimated 54 billion metric tons of carbon, making their fate a significant factor in climate projections.
Tropical Wetlands in South America
South America contains some of the most extensive tropical wetlands on the planet. The Amazon Basin’s floodplains inundate millions of hectares during the wet season, creating seasonally flooded forests and permanent swamps across Brazil, Peru, Colombia, and Bolivia. These floodplain wetlands support extraordinary biodiversity and play a major role in regional water cycling.
Further south, the Pantanal is the world’s largest tropical wetland by continuous area. Covering roughly 42 million acres, it sprawls across three countries: Brazil, Bolivia, and Paraguay. Situated in a broad depression at the headwaters of the Paraguay River, the Pantanal floods extensively during the rainy season and then partially dries out, creating a mosaic of marshes, grasslands, and forested islands that support one of the densest wildlife populations anywhere in the Americas.
Central Africa’s Swamp Forests
The Congo Basin, the world’s second-largest river basin at 3.7 million square kilometers, contains massive wetland systems centered on the Cuvette Centrale. This region is the world’s largest tropical peatland, composed primarily of swamp forests that sit over deep layers of waterlogged organic soil. Additional wetlands surround lakes scattered through the southern Congo Basin, including Mai-Ndombe, Bangwelu, Mweru, and Upemba.
Unlike many other global wetlands, Central Africa’s wetland extent is actually projected to increase in coming decades, making it something of an exception to broader trends of wetland loss.
Southeast Asia and the Pacific
Southeast Asia holds extensive tropical peatlands, particularly on the islands of Borneo, Sumatra, and New Guinea. These coastal and lowland peat swamp forests developed over thousands of years in low-lying areas with poor drainage. Indonesia and Malaysia contain the bulk of this peatland, though significant areas also exist in Papua New Guinea and the Philippines. Many of these wetlands have been heavily altered by agriculture and drainage over the past several decades.
Coastal Wetlands and Mangroves
Mangrove forests, a specialized type of coastal wetland, grow along tropical and subtropical shorelines worldwide. They thrive in sheltered tidal zones where rivers meet the sea, and their range is limited primarily by temperature. The largest mangrove systems are found in Southeast Asia, West Africa, the Caribbean, and northern Australia, with smaller stands reaching as far north as Japan and as far south as New Zealand and South Africa. Exact range boundaries vary by region, with poleward limits depending heavily on winter temperatures and rainfall patterns.
Temperate salt marshes replace mangroves at higher latitudes, lining coastlines from the southeastern United States to northern Europe. Estuaries along the Atlantic and Gulf coasts of the U.S., the North Sea coasts of the UK and the Netherlands, and the Yellow Sea coast of China and Korea all support significant tidal wetland systems.
Temperate Wetlands
Temperate regions hold scattered but important wetlands. The Everglades in southern Florida, the Camargue in southern France, the Danube Delta along the Romania-Ukraine border, and the Mesopotamian Marshes in southern Iraq are among the most recognized. In East Asia, the floodplains of the Yangtze River and the wetlands surrounding Poyang and Dongting lakes provide critical habitat for migratory birds.
Australia’s wetlands are concentrated in the tropical north (Kakadu, the Gulf of Carpentaria) and along the Murray-Darling river system in the southeast, though ephemeral wetlands also appear in the arid interior after heavy rains.
Global Protection Efforts
The Ramsar Convention, the international treaty specifically focused on wetland conservation, has designated over 2,500 sites of international importance across 172 countries, covering nearly 2.5 million square kilometers. These protected sites span all wetland types and every inhabited continent, from Arctic bogs to tropical mangroves to high-altitude lakes in the Andes.
Where Wetlands Are Shrinking and Expanding
Globally, an estimated 21% of wetland area has been lost since 1700. The greatest historical losses occurred in Europe and North America, where drainage for agriculture transformed enormous areas of marsh and bog into farmland. More recently, the rate of loss has accelerated in Asia and tropical regions.
Climate projections paint a mixed picture for the coming decades. The Mediterranean, Central America, and parts of South America face consistent projected declines. The western Amazon Basin could lose around 28% of its wetland extent by the end of this century under a moderate-to-high emissions scenario. In the far north, the Hudson Bay Lowlands face a projected 21% decrease, and the Western Siberian Lowlands a 15% decrease, driven largely by permafrost thaw and changing hydrology. Central Africa, by contrast, is one of the few regions where wetland area is expected to grow. The overall global trend shows only modest net changes in total area, but those averages mask dramatic regional shifts that will reshape where the world’s wetlands are concentrated.