The Egyptian expedition to the Red Sea 1934/35

Six months after the return of the Egyptian Research Vessel ‘MABAHISS’ from its nine month voyage in the Indian Ocean with the John Murray Expedition, an Egyptian Expedition was sent to the Northern Red Sea from December 1934 to February 1935. During these two months, ‘MABAHISS’ carried out four cruises in order to collect samples and makk observations on the geology of small isolated islands, algae, coral reef formation, bottom fauna, bottom sediments, bathmetry, and physical and chemical oceanography. Using the newly developed echosounder, the ship made a detailed bathymetric survey of the Northern Red Sea and Gulf of Aqaba, where the deepest spots, which became known as “Mabahiss Deep I” and “Mabahiss Deep II” respectively, were discovered in the two basins. ‘MABAHISS’ made 10 oceanographic sections and 103 stations of which 47 were oceanographic stations. Equipped with more accurrate equipment than the Austrian ‘POLA’ Expedition (1895–1896), the ‘MABAHISS’ investigations in physical and chemical oceanography revealed several major phenomena for the first time, such as the adiabatic increase of temperature in the Gulf of Aqaba, and the intermediate layer of minimum oxygen and the intermediate maximum of phosphate in the Red Sea. The exchange of water between the Red Sea and Gulf of Agaba in the Strait of Tiran, the formation of deep and bottom water in winter in the Northern Red Sea, and the circulation north of 24°N in the Red Sea, were described for the first time.