I had an overnight stay in Swakopmund as part of my two week road trip through Namibia. I extended the overnight a bit so I could do a 4x4 tour of Walvis Bay and Sandwich Harbor, with a ride through the dunes. The coastline to the harbor is the endless Atlantic Ocean with dune after dune backing up the beach.
This thing in the left quarter of the photo looked like a giant rock to me, but actually, it's sediment and mud built up over time. Saw several of these build ups in the area. Impressive considering the continued waves coming in.
The coast in route to Sandwich Harbor.