Gavkhouni (Persian: گاوخونی, Gāvkhūnĩ) also written as Gavkhuni or Batlaq-e-Gavkhuni, located in central Iran, east of city of Esfahan, is the terminal basin of the Zayandeh River. Gavkhouni is a salt marsh with a salinity of 315‰ and an average depth of about 1 m. The salt marsh can dry up in summer. The Zayandeh River originates in the Zagros mountains and travels around 300 km, before terminating in Gavkhouni.
Gavkhouni receives pollution from Esfahan and other urban sources. Esfahan is a major oasis city on the Zayandeh River with a population over 1.5 million.
The marshes were designated a Ramsar site in 1975.