Mesquite Flat Sand Dunes Sprawling 14 square miles across the widest part of Death Valley, these dunes are the best known and easiest to access in the park. The highest dune is about one mile from here, but many dunes must be crossed to get there. There is no trail in the dunes so you are free to explore on foot wherever you please. A large area of rarely visited dunes is to the east where you may find footprint-free sand for photography.