The Red Sea got its name from the red bacteria that inhabit the top of the water. It could also be called this because of the people who used to inhabit its shores and because of the direction that it is in relation to an old Mediterranean way of identifying directions.
There is no definitive reason for the way this sea gleaned its mysterious name, but many believe that it could be a combination of all of the factors. The sea contains a special kind of bacteria that is known as sea sawdust. This bacteria sits on the top of the sea and can give it a slightly red hue if the timing and lighting are right. The Himyarites were a group of ancient people who lived along the shores of the sea. These people were associated with the color red and the sea could have been named due to their prominence in the area.
In ancient Mediterranean times, the directions were referred to as colors. Black, red, green and white were definitive of North, South, East and West. The Red Sea was to the south and was often referred to as the sea of the south, or Red Sea in the language of the ancient directions.