Algodones Dunes / Imperial Sand Dunes

The Algodones Dunes is a large erg (sand dune field) located in the southeastern portion of the U.S. state of California, near the border with Arizona and the Mexican state of Baja California. The field is approximately 72 kilometers long by 10 kilometers wide (45 miles by 6 miles) and extends along a northwest-southeast line that correlates to the prevailing northerly and westerly wind directions. The name "Algodones Dunes" refers to the entire geographic feature, while the administrative designation for that portion managed by the Bureau of Land Management is the Imperial Sand Dunes Recreation Area (sometimes called the Glamis Dunes). The Algodones Dunes are split into many different sections. These sections include Glamis, Gordon's Well, Buttercup, Midway, and Patton's Valley. The Spanish word algodones translates to the English word cotton.

The dunes are located west of the Chocolate Mountains in Imperial County, and are crossed by Interstate Route 8 and State Route 78, which passes through the old train stop of Glamis at the eastern edge of the dune field. The northwestern end is located at 33°8′53″N 115°19′29″W / 33.14806°N 115.32472°W / 33.14806; -115.32472 about 18 km (11 miles) east of Calipatria, California, and the southeastern end is located at 32°41′4″N 114°46′7″W / 32.68444°N 114.76861°W / 32.68444; -114.76861 near Los Algodones in Mexico about 10 km (six miles) west of Yuma, Arizona. The dunes are also now separated at the southern end by agricultural land (see accompanying photo) from the much more extensive Gran Desierto de Altar, to which they once were linked as an extreme peripheral "finger". The only significant human-made structures in the area are the All-American Canal that cuts across the southern portion from west to east and the Coachella Canal on the western edge.