Spoiler There are many theories about how the Red Sea got its name. Scientists believe it is because, occasionally, the sea becomes filled with blooms of the Cyanobacteria Algae (Trichodesmium Erythraeum,) which, upon dying, turns the usually blue-green water a reddish-brown.
The Red Sea derives its name from a primitive plant in its water that has a red pigment in its cell. If these are gathered together in millions, they give a definite red tinge to the water.
