This a photo of dune 45 in Namibia it's popular to climb. It was one of the first dunes to be open to the public
<a href="//commons.wikimedia.org/wiki/User:Bizcallers" title="User:Bizcallers">bizcallers</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>