Hydrographic parameters of the water column in the central and northern Red Sea were determined during four hydrocast stations (Tab.4). Sound velocity (m/s), temperature (°C ), and light transmission (%) were recorded with depth (pressure in dbar) from sea surface down to the seafloor with bottom contact (Fig.21). Northern Red Sea waters show a general decrease in temperatures from surface water temperatures (23.3-25.3°C ) down to 21.7°C at about 200 m water depth. The measured temperature of 21.7°C of the Red Sea Deep Water is uniform down to the seafloor. However, if brines are present in depressions at the seafloor the temperature rises within a thin brine/seawater interface to higher temperatures in the brine. Surface waters are slightly warmer (24.3°C ) in the central Red Sea at 22- 23N than in the Northern Red Sea between 26 and 27N (23.4-24°C ). A prominent thick layer of less saline and cold water compared to the underlying water mass was detected in the Central Red Sea Area. The upper water mass is possibly derived from the north-heading current with waters from the Strait of Bab el Mandeb.