Psou River
Psou River (; ; ; ; ) is a river in the  West Caucasus, bordering the Gagra Range of Georgian Region of Abkhazia to the east. It flows along the southern slopes of the Greater Caucasus Mountain Range and forms a part of the border between Georgia and Russia. Its source in the Aigra Mountain, and it flows into the Black Sea. The Psou is  long, and the drainage basin is approximately . Between the mouth of the river and the mouth of the Mzymta River is a "sandy depositional foreland", which is approximately  in length and  wide.

The principal tributaries of the Psou are the Besh and the Pkhista. Between 1913 and 1955 there was a hydrological station in operation at Leselidze, roughly  upstream of the river 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.