Muslim pilgrims perform prayers in Arafat during the annual hajj pilgrimage, outside the holy city of Mecca, September 23, 2015. [Photo/Agencies]

Human chains

The Saudi authorities deploy 100,000 police and vast numbers of stewards to ensure safety and help those who lose their way. They have also invested in expensive infrastructure, including a new urban railway, to ferry pilgrims around safely. They give useful tips like noting the number of the mosque gate they use.

But in a crowd of such size, many fall back on their own techniques.

The most disciplined groups seen on Tuesday included parties of Asian pilgrims walking hand-in-hand to stay together and a line of African Muslims who each held a shoulder of the person in front.

Other groups followed more experienced companions holding up sticks or colored umbrellas, while all around were pilgrims talkling into disposable mobile phones they bought to contact friends or relatives in case they got lost.

"You make sure you come back the same route," said Abdulrahman, a pilgrim from Taiz in Yemen, where Saudi-backed forces are battling the Houthi militia. "The best thing is to write down the details of routes you go along," he added.