The Red Sea is one of the most saline bodies of water in the world, owing to high evaporation. Salinity ranges from between ~36  in the southern part because of the effect of the Gulf of Aden water and reaches 41 ‰ in the northern part, owing mainly to the Gulf of Suez water and the high evaporation. The average salinity is 40 ‰. (Average salinity for the world’s seawater is ~35 ‰ on the Practical Salinity Scale, or PPS; that translates to 3.5% actual dissolved salts.)

The salinity of the Red Sea is greater than the world average, approximately 4 percent. This is due to several factors:

  1. High rate of evaporation and very little precipitation.
  2. Lack of significant rivers or streams draining into the sea.
  3. Limited connection with the Indian Ocean, which has lower water salinity.