Is the Red Sea red? If so, why?
Of course it's not actually red, but sometimes it appears that way. Located between the East African coast and the Saudi Arabian peninsula, the Red Sea got its name because of a type of algae called Trichodesmium erythraeum, which is found in the sea. When these blooms of algae die off they appear to turn the blue-green color of the ocean to a reddish-brown.
Follow this link to learn more about the World's Largest Oceans and Seas.
—The Fact Monster