Gorgan Bay (GB) is a semi-enclosed basin located southeast of the Caspian Sea (CS), Iran. The bay was registered as a biosphere reserve in 1976 and had an international focus on conservation. GB severely suffers from low water quality and water level. A hydrodynamic model was used to determine its general circulation, differences in temperature, water elevation, and current speed. This investigation includes the study of current vectors' profiles and analyzing the effects of rivers and air pressure in the circulation of this water body. The average current speed was determined to be 0.1 m/s through the bay. The lowest and highest temperatures were investigated and were -0.53°C and +36.57°C, respectively. The general circulation is mostly counter-clockwise. Water elevation and temperature inside GB always follow a seasonal sinusoidal pattern. This paper neglects the effects of rivers on GB hydrodynamics due to their insignificance discharge. Also, the air pressure has a profound effect on the water level. Current vectors showed that while current speed inside this water body has decreased in the past decade, the temperature increased by almost 7°C.