Introduction
While length gets most of the attention, width is equally impressive. Some rivers expand so dramatically during flood season that they swallow entire landscapes.
Width varies tremendously depending on the season and where you measure. Here are the rivers known for their jaw-dropping breadth.
1. Rio de la Plata
- Maximum Width: 220 km (137 mi)
- Location: Argentina & Uruguay
- Length: 290 km
Often considered an estuary rather than a river, the Rio de la Plata is the widest river-like body of water on Earth. At its mouth between Uruguay and Argentina, it stretches 220 km across.
Buenos Aires and Montevideo, two major South American capitals, sit on opposite shores of this massive waterway.
2. Amazon River
- Wet Season Width: 48 km (30 mi)
- Dry Season Width: 1.6-10 km
- Location: South America
During the rainy season, the Amazon can expand to 48 km wide in its lower reaches. The river floods vast areas of surrounding rainforest, creating a unique seasonally flooded ecosystem.
Even in the dry season, the Amazon remains impressively wide at several kilometers across in many sections.
3. Congo River
- Maximum Width: 16 km (10 mi)
- Location: Central Africa
- Notable Feature: Malebo Pool
The Congo River widens dramatically at Malebo Pool (formerly Stanley Pool), where it expands to about 16 km across. This lake-like widening sits just upstream of Kinshasa and Brazzaville.
Below the pool, the river narrows into the Livingstone Falls, a series of rapids dropping 270 meters.
4. Brahmaputra River
- Maximum Width: 20 km (12 mi)
- Location: India, Bangladesh
- Length: 3,848 km
In the plains of Bangladesh, the Brahmaputra can spread to nearly 20 km during monsoon season. It merges with the Ganges to form the world's largest river delta.
The river carries enormous amounts of sediment, constantly shifting channels and creating new islands.
5. Ganges River
- Maximum Width: 12 km (7.5 mi)
- Location: India, Bangladesh
- Drainage Basin: 1.08 million km²
The Ganges widens significantly as it flows through the flat Indo-Gangetic Plain. During monsoon flooding, it can reach 12 km across in some stretches.
The Ganges-Brahmaputra Delta is the world's largest delta, covering about 100,000 km².
6. Ob River
- Maximum Width: 60 km (37 mi) at Gulf of Ob
- Location: Russia
- Length: 3,650 km
The Ob River in Siberia has an extraordinarily wide estuary. The Gulf of Ob stretches up to 80 km wide and extends 800 km inland from the Kara Sea.
In its lower reaches, the river itself can be up to 20 km wide during spring flooding.
7. Mekong River
- Maximum Width: 14 km (8.7 mi)
- Location: Southeast Asia
- Countries: 6 nations
The Mekong dramatically widens near its delta in Vietnam and Cambodia. During the wet season, it floods vast areas including Cambodia's Tonle Sap lake, which expands fivefold.
The Mekong Delta is one of the most productive agricultural regions in the world, known as Vietnam's "rice bowl."
8. Yangtze River
- Maximum Width: 11 km (6.8 mi)
- Location: China
- Near: Mouth at East China Sea
The Yangtze widens significantly near its mouth at the East China Sea. Shanghai sits on the southern bank where the river is several kilometers across.
Upstream, the river passes through the dramatic Three Gorges, where it narrows to just 100 meters in some places.
9. Mississippi River
- Maximum Width: 18 km (11 mi)
- Location: United States
- Notable Section: Lake Winnibigoshish area
The Mississippi reaches its widest point near Lake Winnibigoshish in Minnesota. During major floods, the lower Mississippi can spread across its entire floodplain.
The 1927 Great Mississippi Flood covered 70,000 km², the most destructive river flood in US history.
10. Paraná River
- Maximum Width: 5 km (3.1 mi)
- Location: South America
- Length: 4,880 km
The Paraná is consistently wide for much of its course through Brazil, Paraguay, and Argentina. Its width makes it a major shipping waterway for South American trade.
Near its confluence with the Paraguay River, both rivers create a vast wetland system.
Key Facts
- The Rio de la Plata is so wide that standing on one shore, you cannot see the other side.
- River width varies dramatically between wet and dry seasons, sometimes by a factor of 10 or more.
- Many of the world's widest rivers are in tropical regions with heavy seasonal rainfall.
- Wide rivers often create vast floodplain ecosystems that support enormous biodiversity.
- The Ob Gulf is the world's longest estuary and one of the widest river mouths.
Fun Facts
- The Amazon River is so wide in places that it was called "The River Sea" by early European explorers.
- During floods, the Brahmaputra creates a temporary island called a "char" that can be inhabited and then disappear.
- The Rio de la Plata is technically neither a river nor an estuary but is classified as a "marginal sea" by some geographers.
- Some sections of the Ob River are so wide that special ice roads are built across them in winter.
Final Thoughts
River width tells a different story than length. These enormous waterways showcase the incredible power of water to reshape landscapes, create ecosystems, and challenge human engineering on a massive scale.