If you zoom in a larger version of the picture, you can see that there’s what looks to be a group of men just hanging out on a ridge. Looking up from them, I’m looking southeast down what is more or less the length of the dunes. The dunes are a huge, relatively narrow, strip about 45 miles (72 km) long and 6 (9.7 km) miles wide running northwest-southeast from just across the border in Mexico up through Imperial County of California. Wikipedia has some wonderful pictures of the dunes from space and then of riders at night – links are below. In the space photo, the road we’re on can barely be seen as a thin line across the dunes on the left side of the picture.

Night: en.wikipedia.org/wiki/Algodones_Dunes#/media/File:Glamis_Presidents_263.jpg
From space: en.wikipedia.org/wiki/Algodones_Dunes#/media/File:AlgodonesDunes_ISS011-E-11543.jpg