The Altar desert is located above the northeast corner of the Sea of Cortez (Gulf of California).
The region is also part of the 2 million-acre El Pinacate/Gran Desierto del Altar Biosphere Reserve, a Mexican National Preserve.
The fishing village of El Golfo lies at the southwestern corner of the desert.
The Altar may be reached from San Luis Rio Colorado, south of Yuma Arizona.
Most of the area is protected; there are a few routes through the desert (next to the railroad tracks) to El Golfo. Offroad cross-country travel is prohibited, though locals and American off-road groups still traverse the desert illegally on a regular basis.