Glamis, about 2 hours east of San Diego, 40 miles long and 5 wide of sand dunes. Due to environmentalists, only 40% of the dunes is open to atvs, and that means it's still the largest sand dunes for off roading vehicles in the USA

The dunes were used to film parts of Road to Morocco, Flight of the Phoenix, Tobruk, Stargate, Resident Evil: Extinction and the Tatooine scenes in Return of the Jedi.