There are at least seven theories. a) Its original Hebrew/Biblical name meant �Sea of Reeds', so it is possible that the name should really be �the Reed Sea'...ie �red' is just, in effect, a mis-spelling. b) Early Egyptian sailors - long before the Suez Canal was dug, obviously - referred to the Gulfs of Suez and Aqaba as the �end' seas. It's possible that changed over time to �red', because the Bible itself refers to both �yam soph' = end sea and yam suph = red sea. c) It may relate to a surface reflection of the pink-coloured coral which is common there or d) to a sort of algae that appears on the surface from time to time. e) There is some suggestion that it comes from the water's colour when seen from the eastern side at sunset and f) that it is a reflection of the red-tinged mountains that border it. g) Finally, there was reputedly an ancient King Erythrus who ruled territory nearby and �erythros' in Greek means �red'. Take your pick!