The Psou (; ; ka, ფსოუ; ; ) is a river in the

West Caucasus The Western Caucasus is a western region of the North Caucasus in Southern Russia, extending from the Black Sea to Mount Elbrus. World Heritage Site The Western Caucasus includes a natural UNESCO World Heritage Site (named Western Caucasus), ...

, bordering the

Gagra Range Gagra Range (; ka, გაგრის ქედი, tr; ; ) is a mountain range of the Greater Caucasus in Abkhazia, Georgia.The range runs between the valleys of the Bzyb and Psou rivers to the south of the Caucasus Major, in a general North ...

to the east. It flows along the southern slopes of the

Greater Caucasus The Greater Caucasus, ''Didi K’avk’asioni''; is the major mountain range of the Caucasus Mountains. It stretches for about from west-northwest to east-southeast, from the Taman Peninsula of the Black Sea to the Absheron Peninsula of t ...

Mountain Range and forms a part of the border between

Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...

(

Abkhazia Abkhazia, officially the Republic of Abkhazia, is a List of states with limited recognition, partially recognised state in the South Caucasus, on the eastern coast of the Black Sea, at the intersection of Eastern Europe and West Asia. It cover ...

) and

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

. Its source is in the Aigra Mountain, and it flows into the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

. The Psou is long, and the

drainage basin A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

is approximately . Between the mouth of the river and the mouth of the

Mzymta The Mzymta (; Abkhaz: Мӡы́мҭа; , ''Mezmytha'') is a river in Northwestern Caucasus, flowing through Mostovsky District and the city of Sochi ( Adlersky City District) of Krasnodar Krai, Russia. The Mzymta is the largest river in Russia ...

is a "sandy depositional foreland", which is approximately in length and wide. The principal tributaries of the Psou are the Besh and the

Pkhista The Pkhista ( ka, ფხისთა) is a river in the West Caucasus, near the border between Georgia (country), Georgia (Abkhazia) and Russia. It has a length of Alternate url/ref> and flows into the left (eastern) bank of the Psou to the south ...

. Between 1913 and 1955, a hydrological station was in operation at Leselidze, roughly upstream of the river's mouth. The Psou gained notoriety as a smuggling route out of the country, by-passing Russian controls on the border. As of 2008 it was still designated as a transboundary river which lacked an international cooperation agreement as part of the UNECE Water Convention.

References

{{Rivers of Georgia Rivers of Krasnodar Krai Rivers of Georgia (country) Rivers of Abkhazia International rivers of Europe International rivers of Asia Georgia (country)–Russia border Smuggling routes Drainage basins of the Black Sea