The Sahara Desert has two major dunes that are tourist attractions – Erg Chebbi near Merzouga, and Erg Chigaga near M'hamid.
Both dunes are difficult to access – you can only reach them via 4x4 vehicles or camels, or by walking – although Erg Chebbi is better known and more visited. Erg Chigaga offers a somewhat wilder dune experience. You can do camel treks, 4x4 excursions, or overnight camping trips at Erg Chigaga, all provided you've got a guide. There is even a luxury camp at Erg Chigaga, with 10 large tents or a smaller private camp with four tents.
It takes roughly nine hours to reach Erg Chigaga from Marrakech, including two hours that's only accessible via 4x4s. The Erg Chigaga Luxury Camp is closed from June 7 to September 7 because of the intense summer heat.