The Answer:

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 Editors