Most oceans and seas stay relatively stable over human lifetimes, but the Red Sea is an active participant in plate tectonics. The Red Sea is actually a flooded rift valley where the Arabian Plate and the African Plate are pulling away from each other. This process is creating a new ocean. As the plates move apart at a rate of about 1 centimeter per year, the Red Sea is slowly widening. Geologists believe that in millions of years, the Red Sea will become a massive ocean similar to the Atlantic. This makes it a rare place where humans can observe the birth of an ocean in real-time. This is the opposite of the Mediterranean Sea, which is slowly shrinking as Africa moves toward Europe.