"Surely, but of great use to the world at large," Captain Nemo said. "The ancients well understood the usefulness to commerce of connecting the Red Sea with the Mediterranean, but they never dreamed of cutting a canal between the two, and instead they picked the Nile as their link. If we can trust tradition, it was probably Egypt's King Sesostris who started digging the canal needed to join the Nile with the Red Sea. What's certain is that in 615 B.C. King Necho II was hard at work on a canal that was fed by Nile water and ran through the Egyptian plains opposite Arabia. This canal could be traveled in four days, and it was so wide, two triple-tiered galleys could pass through it abreast. Its construction was continued by Darius the Great, son of Hystaspes, and probably completed by King Ptolemy II. Strabo saw it used for shipping; but the weakness of its slope between its starting point, near Bubastis, and the Red Sea left it navigable only a few months out of the year. This canal served commerce until the century of Rome's Antonine emperors; it was then abandoned and covered with sand, subsequently reinstated by Arabia's Caliph Omar I, and finally filled in for good in 761 or 762 A.D. by Caliph Al-Mansur, in an effort to prevent supplies from reaching Mohammed ibn Abdullah, who had rebelled against him.