Abstract—Anzali Lagoon is a coastal liman, or wetland in the Caspian Sea near Anzali Port, in the northern Iranian province of Guilan. The lagoon divides Anzali city into two parts. Water exchange phenomenon and physical properties of seawater along connecting channel between the Caspian Sea and Anzali Lagoon were assessed. The research was based on field observation on 6 sampling stations during warm and cold seasons. Observations were performed by a portable CTD Ocean Seven 316 probe. The parameters ranges in the warm and cold seasons were different. Based on data, water temperature in vertical direction changed between 27.5-25 centigrade in June and it ranged between 9.3-7.5 centigrade in February. Mean values of water salinity in cold season were less than that in warm season in the Anzali Lagoon connecting channel. Variations of salinity were around 12 psu in warm season while salinity values in cold season observed about 7.5 psu. According to high correlation between seawater density and temperature in the Lagoon connecting channel as well as the Caspian Sea, vertical structures of water density and temperature were in agreement.