Red Sea is a direct translation of the Greek Erythra Thalassa (Ερυθρὰ Θάλασσα) and Latin Mare Rubrum (alternatively Sinus Arabicus, literally "Arabian Gulf"), Arabic Al-Baḥr Al-Aḥmar (البحر الأحمر), Somali Bada Cas and Tigrinya Qeyyiḥ bāḥrī.
The name of the sea may signify the seasonal blooms of the red-coloured Trichodesmium erythraeum near the water's surface.
Another hypothesis is that the name comes from the Himyarite, a local group whose own name means red.
A theory favored by some modern scholars[who?] is that the name red is referring to the direction South, just as the Black Sea's name may refer to North. The basis of this theory is that some Asiatic languages used color words to refer to the cardinal directions. Herodotus on one occasion uses Red Sea and Southern Sea interchangeably.
It is theorized that it was named so because it borders the Egyptian Desert, which the ancient Egyptians called the Dashret or "red land"; therefore it would have been the sea of the red land.
The association of the Red Sea with the Biblical account of the Israelite Crossing the Red Sea is ancient, and was made explicit in the Septuagint translation of the Book of Exodus from Hebrew to Koine Greek in approximately the third century B.C. In that version, the Hebrew Yam Suph (ים סוף) is translated as Erythra Thalassa (Red Sea).
The Red Sea is one of four seas named in English after common color terms — the others being the Black Sea, the White Sea and the Yellow Sea.
The direct rendition of the Greek Erythra thalassa in Latin as Mare Erythraeum refers to the north-western part of the Indian Ocean, and also to a region on Mars.