Erg Chebbi

Where it sits. Erg Chebbi is a sand sea in south-eastern Morocco, hard against the Algerian border, about 28 km from north to south and five to seven kilometres across, with crests rising some 150 metres above the flat hamada — the stony desert pavement — that surrounds it. The village of Merzouga sits on the western lee of the dunes, which is why the erg is often marketed as "the dunes of Merzouga"; the market town of Rissani is 40 km away and Erfoud roughly 60 km north. The contrast at the dune foot is abrupt and is the thing photographs never convey: you drive across grey gravel plain at 60 km/h and then the sand simply begins, a wall of it, with no transition.

The story behind it. This is the Tafilalet, the oasis system fed by the Ziz and Rheris rivers, and it was one of the great termini of trans-Saharan trade. Rissani stands on the site of Sijilmassa, a caravan city that grew wealthy between the eighth and fourteenth centuries on gold moving north from the Sahel and salt moving south; the Alawite dynasty that still rules Morocco came from here. South of Merzouga, the village of Khamlia is home to a community descended from enslaved people brought north across the desert, whose Gnawa music is performed daily and is a genuine local tradition rather than a staged one. West of the dunes, the seasonal lake Dayet Srji fills after winter rain and draws flamingos and waders for a few weeks. Water in this landscape is not always benign: floods beside the dunes in 2006 destroyed buildings and killed three people.

On screen. The erg supplies the postcard Sahara, but most of the film work in this corner of Morocco has been staged on the harder ground of the Erfoud–Rissani corridor an hour north, where crews can move vehicles and build sets.

• The Mummy (1999) began principal photography on 4 May 1998 in Marrakesh, where the production spent two weeks taking down telephone wires and shipping in period cars and camels, then moved to the desert outside Erfoud for the Hamunaptra sequences; the crew dealt with sandstorms, snakes and a medical team rationing rehydration drinks every two hours.
• Spectre (2015) built Blofeld's crater base at Gara Medouar, an eroded horseshoe ridge in the same corridor, and detonated the record-setting kerosene explosion there.
• Prince of Persia: The Sands of Time (2010) spent eight weeks shooting in Morocco in 2008 before moving to Pinewood, and Sahara (2005) shot on location here from November 2003.

Camel-and-dune footage from the erg itself turns up constantly in second-unit and commercial work, which is why the same crest line is recognisable across dozens of productions that were never otherwise shot within 500 km of it.

What you actually see today. The standard visit is an overnight: camels leave the auberges on the western edge in late afternoon, cross an hour and a half of dune field to a bivouac of black wool tents, and return at first light. The sand is orange-red from iron oxide on the grain surfaces and its colour shifts hard through the day, from washed-out yellow at noon to deep rust twenty minutes before sunset. Ridge walking is slower than it looks; a 150-metre dune takes 30 to 45 minutes of collapsing steps, and the technique is to follow the knife edge where the sand is packed rather than the windward face where it gives way. Wind rebuilds the ripple patterns overnight, so the dunes photographed at dawn carry no footprints even after a busy day. Other fixtures: sandboarding down slip faces, 4x4 runs to Khamlia and the old lead-mining ruins at Mfis, and the fossil workshops in Erfoud, where Devonian orthoceras and goniatites are cut and polished out of dark marble quarried nearby.

Getting there and timing. Merzouga is at the end of a paved road from Rissani, about 560 km from Marrakesh via Ouarzazate and the Todra gorge — a two-day drive rather than a day trip, however it is sold. Errachidia airport is 130 km north, and overnight buses run from Marrakesh and Fes. October to November and February to April are the workable seasons: clear, 20 to 25 °C by day, cold after dark, with winter nights near freezing. Summer regularly passes 45 °C. Spring brings the chergui, a hot easterly that fills the air with suspended sand for days and flattens the light entirely.