Although not an estuary in the traditional sense, the Gulf of Suez is an elongated semi-enclosed shallow sea characterized by inverse estuarine circulation. Due to excess evaporation caused by its arid climate, the Gulf experiences increased salinity and a net water loss of about 2 meters per year in water level. This water loss is believed to produce a net inflow of lower salinity surface water from the Red Sea, which lies to the south. The Gulf is categorized as an inverse estuarine system because of its higher salinity at the head and lower salinity at the mouth. Temperature at the head of the sea in the summer decreases rapidly with depth, but during the winter temperature in the water column is more homogeneous.
Salinity decreases from the head of the Gulf to the mouth.
In the vertical direction, salinity is relatively homogeneous in the head of the Gulf and increases with depth at the mouth due to saline Gulf water near the bottom and less saline Red Sea water at the surface. The tidal wave in the Gulf of Suez is in the shape of a standing wave with high and low water at opposite ends of the Gulf. Observed isotherms and isoclines indicate surface inflow of warm, less saline water from the Red Sea and subsurface outflow of colder, more saline Gulf water. Tidal-induced residual circulation was determined to be southward at depth. Northeasterly winds were found to generate surface inflow and subsurface outflow, while the opposite occurred during a northwest wind.