Wetlands are found on every continent except Antarctica, covering roughly 1.4 billion hectares of the Earth’s surface. That’s about 13.4% of the world’s total land area, spread across climates ranging from tropical floodplains to frozen arctic tundra. They form wherever water meets land in a sustained way: along rivers, around lakes, in coastal zones, across vast interior lowlands, and even in high-altitude mountain valleys.
Global Distribution by Region
About 91% of the world’s wetlands are inland freshwater systems, while the remaining 9% are coastal. That split means the vast majority of wetlands sit far from the ocean, fed by rivers, rainfall, snowmelt, or underground springs rather than tides.
The largest concentrations stretch across the northern latitudes. Russia’s West Siberian Lowland holds one of the biggest continuous wetland zones on the planet, a mosaic of peatlands and bogs blanketing millions of square kilometers. Canada’s Hudson Bay Lowlands and the boreal muskegs across northern Canada form another massive belt. These northern peatlands store enormous amounts of carbon in waterlogged soils that have accumulated organic material over thousands of years.
In the tropics, the Pantanal in South America is the world’s largest freshwater wetland at roughly 68,000 square miles, straddling the borders of Brazil, Bolivia, and Paraguay within the upper Paraguay River basin. That makes it more than 20 times the size of the Everglades. The Congo River basin in Central Africa and the Amazon floodplain also contain enormous tropical wetland systems, where seasonal flooding creates vast swamps and marshes that support staggering biodiversity.
Southeast Asia holds extensive wetlands as well, particularly in Indonesia and Myanmar, where peat swamp forests and mangrove coasts line the shoreline. Africa’s inland wetlands include the Okavango Delta in Botswana and the Sudd in South Sudan, one of the largest freshwater marshes on Earth.
Where Wetlands Form in the Landscape
Wetlands don’t appear randomly. They develop in specific landscape settings where the combination of water source, terrain shape, and soil type keeps the ground saturated long enough for wetland plants and soils to take hold. The U.S. EPA recognizes five major landscape positions where this happens: riverine, depressional, slope, flat, and fringe.
Riverine wetlands form along rivers and streams, where periodic flooding spreads water across the floodplain. These are some of the most common wetlands worldwide and include the bottomland hardwood forests found across the southeastern United States. Depressional wetlands sit in low spots in the landscape, essentially natural bowls that collect rainwater or groundwater with no outlet. Prairie potholes across the northern Great Plains are a classic example.
Slope wetlands occur where groundwater seeps out along hillsides or at the base of slopes, often creating fens or spring-fed marshes. Flat wetlands develop on level terrain with poorly drained soils, where rainfall simply has nowhere to go. Fringe wetlands border lakes, estuaries, or the ocean, shaped by wave action and water level changes. Mangrove forests and salt marshes along tropical and temperate coasts fall into this category.
Wetlands Across the United States
Alaska dominates the picture in the U.S. with roughly 170 million acres of wetlands, more than the other 49 states combined. These range from coastal salt marshes and tidal flats to interior bogs, fens, tundra, and wet meadows spread across the state’s vast, sparsely populated landscape.
Among the lower 48 states, Florida leads with about 11 million acres. Most are forested freshwater habitats on stream floodplains, in small depressions, and across wet flatwoods. The Everglades in southern Florida is the most famous, a massive freshwater marsh that historically received water flowing south from the Kissimmee River and Lake Okeechobee basin, though today it depends largely on managed canal releases.
Minnesota holds roughly 9.5 million acres, about half what existed before European settlement. Its wetlands are notably diverse: expansive northern peatlands in the boreal zone transition to small, scattered prairie potholes farther south and west. Those prairie potholes, while individually small, are critically important breeding habitat for North American waterfowl.
Georgia has more than 7.7 million acres, concentrated in the coastal plain where river floodplains are widest and tidal freshwater swamps meet estuarine marshes. The Okefenokee Swamp near the Florida border is one of the largest freshwater wetlands in the country, a patchwork of emergent marshes, forested swamps, and open water. Texas follows closely with about 7.6 million acres, including the bottomland hardwood forests and swamps of East Texas, the marshes and tidal flats along the Gulf Coast, and the playa lakes scattered across the High Plains in the western part of the state.
Coastal Wetlands and Their Locations
Though they make up only 9% of global wetland area, coastal wetlands are concentrated in some of the most ecologically and economically important zones on Earth. Mangrove forests line tropical and subtropical coastlines throughout Southeast Asia, West Africa, Central America, and northern Australia. They thrive in sheltered, low-energy shorelines where tidal waters carry sediment and nutrients.
Salt marshes replace mangroves in cooler climates, lining the coasts of the eastern United States, northwestern Europe, and parts of South America and Australia. Tidal flats, where fine sediments are exposed at low tide, appear in all of these regions and serve as crucial feeding grounds for migratory shorebirds. Major estuaries, where rivers meet the sea, almost always support a surrounding complex of coastal wetlands. The Chesapeake Bay, the Rhine Delta, and the Mekong Delta are all examples.
How Much Has Been Lost
Since 1970, an estimated 411 million hectares of wetlands have disappeared globally, roughly 22% of the total. The annual rate of decline currently sits at about 0.52%, driven by agricultural conversion, urban development, and changes in water management. Losses have been particularly severe in densely populated regions: Europe and the eastern United States lost the majority of their original wetlands centuries ago, while tropical wetlands in Southeast Asia have been drained rapidly in recent decades for palm oil plantations and rice paddies.
The remaining 1.4 billion hectares provide ecosystem services valued at up to $39 trillion annually, including flood control, water filtration, carbon storage, and habitat for fish and wildlife. The Ramsar Convention, an international treaty focused on wetland conservation, has designated over 2,530 Wetlands of International Importance covering about 2.58 million square kilometers, representing roughly 14 to 17% of the world’s remaining wetlands. These protected sites span 172 countries, from tiny urban marshes to vast wilderness peatlands, marking the locations where international commitments to wetland preservation are strongest.