Persian Gulf Hydrography
Hydrography and bathymetry of Persian Gulf is amongst low-depth and marginal seas which is different from its surrounding seas in natural and structural respects. Attention to depth reveals this structural distinction. Oman and Aden seas which are ocean branches are as deep as 2,000 meters and Arabian Sea is as deep as 5,000 meters. Red sea is also more than 1,000 meters deep on average. But as we approach Persian Gulf water depth abruptly decreases (M. H. Ramasht, 59:1997)
In fact subsidence caused by tectonics has caused bottom of strait of Hormoz to be locally deep that in some regions this depth also reaches 200-300 meters, but deepest district of Persian Gulf is located close to Abu Musa Island amounting to 126 meters (geographical organization, 2003).
Construction and development land caused by above mentioned tectonics has created a 70-90 meter deep trophy (hollow area) from strait of Hormoz and along coastline of Iran with approximate length of 100 kilometers. Strait of Hormoz and mentioned abyss are separated from each other by a wide sea ridge (Stephen. A. Swift 2003:3)
This trophy collects heavier and higher density water in it and sometimes hinders sea currents in this part from Persian Gulf. (A. R. G. Price and etc., 1993:37). Depth of Persian Gulf gradually decreases from strait of Hormoz towards northwest and reaches 36 and 25. In southern coasts due to growth of coralloid masses water depth decreases again and reaches even less than 20 meters.
Source: Persian Gulf region geopolitics, geographical organization of armed forces of country