“Biggest river” has three answers: the longest channel, the most water, or the largest land drained. Sort the table three ways and the winners change. Every figure here is an estimate: rivers wander, and measurers disagree about where a river begins and ends.
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Drawer: The World’s Great Rivers · Quiz: Great Rivers, 8 questions
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Rain falls on hills and runs downhill. Little streams join into bigger streams, and bigger streams join into a river, until the river reaches the sea. The land that drains into one river is called its watershed. Every place, even your school, is in a watershed. Which river does your rain go to?
Click a column to sort. Florida’s rivers are listed below for scale.
| # | River | Continent | Length, km | Flow, m³/s | Basin, km² | Mouth |
|---|
≈ All figures are rounded estimates from standard references (Encyclopaedia Britannica, USGS, national water agencies); flow is the long-term average at or near the mouth. Lengths of joined rivers (Mississippi–Missouri, Ob–Irtysh) are measured from the farthest headwater.
Each dot marks a river’s mouth; its size grows with the water it carries. Click a dot for the river.
Most reference books list the Nile (about 6,650 km) as the longest river and the Amazon (about 6,400 km) second. But where a river “begins” depends on which headwater stream you choose, and how you measure its winding mouth. In 2007 Brazilian researchers argued the Amazon is about 6,992 km; an international expedition launched in 2024 set out to measure both again. Treat the ranking as disputed.
By the water it carries, the Amazon has no rival: on average about 209,000 cubic meters a second reach the Atlantic, roughly a fifth of all the river water flowing into the world’s oceans, and more than the next several rivers together. Fresh water stains the ocean for 100 miles out to sea.
≈ Source: USGS Water Science School; Encyclopaedia Britannica
The Congo is the deepest river measured: in the Inga rapids below Kinshasa, scientists from the U.S. Geological Survey and the American Museum of Natural History found channels more than 220 meters deep in 2008. Fish in the deep, fast water have evolved apart, like island species.
On the Yangtze, the Three Gorges Dam (finished 2012) is the largest power station on Earth, about 22,500 megawatts. Its reservoir stretches some 600 km and displaced more than 1.3 million people. It controls floods and moves ships, and it also traps sediment, changed fish habitat and drowned towns and sites.
≈ Source: China Three Gorges Corporation; Encyclopaedia Britannica
The Colorado once ran 2,330 km to the Gulf of California. Today dams and canals send nearly all its water to farms and to cities from Denver to Los Angeles, and in most years the river ends in the desert before reaching the sea. Lakes Mead and Powell, its great reservoirs, fell to record lows in 2022.
≈ Source: U.S. Bureau of Reclamation; USGS
The Amu Darya and Syr Darya once filled the Aral Sea, then the fourth-largest lake in the world. From the 1960s, Soviet planners diverted them to grow cotton in the desert. By the 2010s the sea had lost most of its water, leaving fishing boats on dry sand and salt storms. A dam built in 2005 has brought part of the northern Aral back.
Rivers gave cities water, food, power and a road to the sea. Look at the list: Cairo on the Nile, Shanghai at the Yangtze mouth, New Orleans and St. Louis on the Mississippi, Vienna, Budapest and Belgrade on the Danube, Rotterdam on the Rhine’s mouth, Kinshasa and Brazzaville facing each other across the Congo.
Source: Encyclopaedia Britannica
Where a slow river meets the sea it drops its mud and sand and builds a delta. The Ganges–Brahmaputra delta of Bangladesh and India is the largest; the Nile, Mississippi and Mekong deltas feed tens of millions. Dams upstream trap the mud, so many deltas now sink and shrink: Louisiana loses wetland about the size of a football field every 100 minutes.
≈ Source: USGS, “Louisiana’s Changing Coastal Wetlands” (2017)
Bradenton sits on the south bank of the Manatee River, about 58 km (36 miles) long, which rises in the east of the county, is dammed to form Lake Manatee (the county’s drinking water), and widens into a tidal estuary to Tampa Bay. Hernando de Soto may have landed near its mouth in 1539; the De Soto National Memorial marks the place.
≈ Source: Manatee County Utilities; National Park Service, De Soto National Memorial
The St. Johns, Florida’s longest river at about 500 km (310 miles), flows north, from the marshes near Vero Beach to the Atlantic at Jacksonville. It drops only about 9 meters in all that distance, one of the flattest major rivers in North America, so the tide can be felt more than 100 miles upstream.
The Suwannee (about 396 km) runs from the Okefenokee Swamp in Georgia to the Gulf, fed by dozens of clear springs. The Peace River (about 171 km), from Polk County to Charlotte Harbor, is famous for fossil shark teeth and was once mined for phosphate. The Myakka (about 106 km) winds through Myakka River State Park near Sarasota, one of Florida’s two state-designated Wild and Scenic Rivers.
≈ Source: Florida Department of Environmental Protection; Southwest Florida Water Management District
| Florida river | Length, km (miles) | Flow, m³/s | Basin, km² | Mouth | Note |
|---|---|---|---|---|---|
| St. Johns | 500 (311) | 225 | 22,800 | Atlantic Ocean at Jacksonville | Flows north; drops only about 9 m in its whole length. |
| Suwannee | 396 (246) | 300 | 25,770 | Gulf of Mexico | From the Okefenokee Swamp; fed by springs. |
| Peace | 171 (106) | 33 | 6,086 | Charlotte Harbor | Fossil shark teeth; phosphate country. |
| Myakka | 106 (66) | 7 | 1,500 | Charlotte Harbor | A Florida Wild and Scenic River. |
| Manatee | 58 (36) | 5 | 930 | Tampa Bay at Bradenton | Bradenton’s river; Lake Manatee reservoir. |
≈ Florida figures: Florida DEP, St. Johns River and Southwest Florida water management districts, USGS gauges; flows are rough long-term averages.
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