From one vlei, we notice tiny movements atop one of the distant dunes, the outlines of two climbers reaching a summit.

CNN: Romancing the dune in Namibia

In a few spots, the water remains, forming shallow marshlands called "vlei" (pronounced "vlay") that support trees, birds, frogs and other small wildlife.

CNN: Romancing the dune in Namibia

Now, blackened petrified acacias rise hauntingly from the hard vlei floor.

CNN: Romancing the dune in Namibia