A "barchan" sand dune is typically arc-shaped, like a crescent moon, with two "horns" on the downwind side. The distance between the "points" of the horns can be a few feet to hundreds of feet.
These sand dunes are found on Magdalena Bay, which lies along the west coast of Baja California. The bay is protected from the Pacific Ocean by the islands of Isla Magdalena and Isla Santa Margarita. Its mangrove swamps provide sanctuaries for sea bird. Fishing is good and gray whales abound.