Why did the Namib Desert appear next to the ocean?

Namib is one of the harshest as well as coldest deserts on the continent. And it was formed due to the fact that there is a minimum amount of moisture in this area. Although the ocean is nearby, the cold and humid air of the ocean collides with the hot and dry air of the desert. Also, this process is blocked by vertical air currents, and therefore, if precipitation is formed, it is very very weak. Here only occasionally dense fog appears on the surface.