This list covers 40 rivers with names starting with the letter I, running from “Indus” to “Isis.” These rivers span every continent except Antarctica, ranging from massive transboundary waterways that cross several countries to small local streams. People rely on them for drinking water, irrigation, hydropower, transportation, and fishing, and many have shaped the history and culture of the regions they flow through.

Rivers are natural channels of flowing water that carry rainfall and melted snow from higher ground down to lakes, seas, or oceans. Along the way, they shape landscapes, support farming, and often mark borders between nations. The Isis, for example, is simply the traditional name given to the Thames as it passes through Oxford, showing how the same river can carry different names in different places.

Below you’ll find the table with each river’s name, countries, length, type, and description.

River: the name of each river on this list, listed alphabetically from “Indus” to “Isis” so you can find any one quickly.

Countries: the nations each river flows through, helping you see which waterways cross borders and which stay within one country.

Length (km): the total length of each river in kilometers, giving you a quick way to compare their sizes.

Type: how each river fits into the wider water system, such as a tributary, a transboundary river, or an independent river reaching the sea.

Description: a short summary of where each river flows and why it matters, so you get context beyond the raw numbers.

Rivers

RiverCountriesLength (km)Type
IndusPakistan, India, China3,180Transboundary river
IrrawaddyMyanmar2,170Major national river
IrtyshChina, Kazakhstan, Russia4,248Tributary of the Ob
IshimKazakhstan, Russia2,450Tributary of the Irtysh
IliChina, Kazakhstan1,439Endorheic river
IguazuBrazil, Argentina, Paraguay1,320Tributary of the Paraná
ItapicuruBrazil730Independent river
IvaiBrazil700Tributary of the Paraná
IngodaRussia708Tributary of the Shilka
Iowa RiverUnited States530Tributary of the Mississippi
IzhmaRussia531Tributary of the Pechora
InguletsUkraine549Tributary of the Dnieper
IvinheimaBrazil480Tributary of the Paraná
IncomatiSouth Africa, Eswatini, Mozambique480Transboundary river
IyaRussia468Tributary of the Angara
Illinois RiverUnited States439Tributary of the Mississippi
IputBelarus, Russia437Tributary of the Sozh
IndalsalvenSweden430Independent river
IskarBulgaria368Tributary of the Danube
IijokiFinland370Independent river
IngulUkraine354Tributary of the Southern Bug
IbarKosovo, Serbia276Tributary of the West Morava
IndreFrance265Tributary of the Loire
ImjinNorth Korea, South Korea254Tributary of the Han
IshikariJapan268Independent river
InguriGeorgia213Independent river
IllFrance, Germany217Tributary of the Rhine
IcaPeru220Independent river
Itajai-AcuBrazil200Independent river
IvelEngland40Tributary of the Great Ouse
IpojucaBrazil199Independent river
ItataChile190Independent river
InnSwitzerland, Austria, Germany517Tributary of the Danube
IsarAustria, Germany295Tributary of the Danube
IsereFrance286Tributary of the Rhone
IsonzoSlovenia, Italy136Transboundary river
IJsselNetherlands125Distributary of the Rhine
IwakiJapan102Independent river
ItchenEngland46Independent river
IsisEngland15Local name of the Thames

Descriptions

Indus
One of Asia’s great rivers, flowing from the Tibetan Plateau through India and Pakistan to the Arabian Sea; cradle of the ancient Indus Valley Civilization.
Irrawaddy
Myanmar’s longest and most vital river, running the length of the country from the Himalayas to a fertile delta on the Andaman Sea.
Irtysh
One of Asia’s longest rivers, crossing three countries before joining Siberia’s Ob River on its long journey north.
Ishim
A long steppe river that flows past Kazakhstan’s capital, Astana, before joining the Irtysh in Russia.
Ili
Rises in China’s Tian Shan mountains and flows into Kazakhstan, ending in Lake Balkhash instead of reaching the sea.
Iguazu
Famous for the spectacular Iguazu Falls on the Brazil-Argentina border, before its waters join the Paraná River.
Itapicuru
Flows across Bahia state in northeastern Brazil, draining into the Atlantic Ocean.
Ivai
Runs entirely within Paraná state, Brazil, before joining the larger Paraná River.
Ingoda
A Siberian river in Russia’s Zabaykalsky region that feeds into the wider Amur river system.
Iowa River
Crosses the U.S. state of Iowa through farmland before emptying into the Mississippi River.
Izhma
Winds through Russia’s Komi Republic before joining the Pechora River in the far north.
Ingulets
A Ukrainian steppe river flowing south to meet the Dnieper near the city of Kherson.
Ivinheima
Flows through Mato Grosso do Sul state in Brazil before joining the Paraná River.
Incomati
Crosses three southern African countries before reaching the Indian Ocean near Maputo.
Iya
A Siberian river in Irkutsk Oblast that feeds into the Angara River.
Illinois River
Flows across the U.S. state of Illinois, historically linking the Great Lakes to the Mississippi River.
Iput
A slow, marshy river crossing Belarus and Russia to join the Sozh, part of the Dnieper river system.
Indalsalven
A major Swedish river heavily used for hydropower as it flows toward the Gulf of Bothnia.
Iskar
Bulgaria’s longest river lying entirely within its borders, running from the Rila Mountains to the Danube.
Iijoki
A Finnish river flowing to the Gulf of Bothnia, dammed at several points for hydroelectric power.
Ingul
Flows past the city of Mykolaiv before joining the Southern Bug estuary in Ukraine.
Ibar
Flows from Kosovo into Serbia, long significant as a cultural and political boundary in the region.
Indre
Winds through the Loire Valley’s chateau country before joining the Loire River.
Imjin
Crosses the Korean Demilitarized Zone before joining the Han River near Seoul.
Ishikari
The longest river on the Japanese island of Hokkaido, flowing through farmland to the Sea of Japan.
Inguri
Flows from the Caucasus Mountains through Abkhazia to the Black Sea, home to one of the world’s tallest dams.
Ill
Flows through the Alsace region and the city of Strasbourg before joining the Rhine.
Ica
Runs through southern Peru’s arid Ica Region, sustaining the area’s desert agriculture.
Itajai-Acu
Flows through Brazil’s Santa Catarina state, historically prone to severe flooding in the city of Blumenau.
Ivel
A small English river flowing through Bedfordshire before joining the Great Ouse.
Ipojuca
Crosses Pernambuco state in northeastern Brazil on its way to the Atlantic Ocean.
Itata
Flows from the Andes through central Chile’s wine-growing valleys to the Pacific Ocean.
Inn
A fast Alpine river rising in Switzerland that gives its name to Innsbruck before joining the Danube in Bavaria.
Isar
A scenic Alpine river that flows through Munich, popular for swimming, before joining the Danube.
Isere
A French Alpine river that lends its name to a department, meeting the Rhone south of Valence.
Isonzo
Known for its striking turquoise water and as a bloody front line during World War I.
IJssel
A branch of the Rhine that channels part of its flow north into the IJsselmeer, central to Dutch water management.
Iwaki
Flows through Aomori Prefecture in northern Japan, known for the apple orchards lining its banks.
Itchen
A chalk stream in Hampshire prized for trout fishing, flowing through the city of Winchester.
Isis
The traditional name given to the River Thames as it flows through the city of Oxford.
If you think there is a missing term, let us know using the contact form.