What is an erg (sand sea) in Morocco?

An erg is the proper word for a sand sea: a vast field of dunes built and reshaped entirely by the wind. It is the single landscape every traveller has in their head when they say 'the Sahara' — the soaring, sculpted, apricot-coloured ridges that go on past the horizon. The important thing to understand is that an erg is actually the rarest desert surface in Morocco. Most of the Sahara is flat and stony; the ergs are the dramatic exception, which is exactly why people drive two days to reach them.

Morocco has two ergs worth your time, and they are different beasts. Erg Chebbi, beside Merzouga, is the accessible icon — a compact, ferociously beautiful field of dunes rising to about 150 metres, glowing through every shade of orange between sunrise and sunset. Erg Chigaga, out past M'hamid, is bigger, lower, far more remote, and reachable only by 4x4 over an hour of off-road track. Chebbi is the easy postcard; Chigaga is for travellers who want the dunes without the crowd and are willing to earn them.

What I love about standing in an erg is how alive it is. The sand is never still — you watch the wind smoke off the crests, you see your own footprints erased by morning, you feel the surface shift under you as you climb. Climbing a big dune is genuinely hard work; the sand takes back half of every step. But cresting the highest ridge for sunset, with the whole sea of dunes turning gold and then violet below you, is the moment most people remember longest from their entire Morocco trip.

For travellers, the erg is the reason the long desert drive is worth it. I tell people not to settle for the flatter, stonier 'desert' you can reach in a quick day trip and assume they have seen the Sahara — they have not. Hold out for an erg. Sleep in a camp at the foot of the dunes, ride a camel in for sunset, and wake before dawn to climb for the sunrise. That is the difference between a desert excursion and the desert experience.