Early every morning, in the Gulf of Suez at the top of the Red Sea, ships line up and head in slow procession towards a narrow opening in the desert at the gulf’s north end.

They spend their day moving methodically across the desert, sailing from artificial channel to natural lake and back again, before emerging at dusk, 160km further north at Port Said on the Mediterranean. The same routine is repeated twice a day at Port Said, where two convoys daily head south towards the Red Sea.