Where and how tall is the the largest sand dunes?

The largest sand dunes in the world are found in the Namib Desert in Namibia, specifically in the Sossusvlei area. These dunes, known as "star dunes," can reach heights of over 1,000 feet (about 300 meters). Dune 7, one of the tallest in the region, is often cited as the highest accessible dune for visitors. The striking red color of the dunes is due to the iron oxide present in the sand.