The dunes were built over thousands of years by the wind. Sand from the Sigatoka River and the seabed was blown inland, grain by grain, and piled up into hills. Different winds blow from different directions, so the dunes have curved, rippled shapes that constantly, slowly shift.
Beneath the sand, there is a lot of history. Over many centuries, Fijian people built settlements near here, and objects from those communities - shells, pottery and more - have been preserved under the sand. The dunes are now a national park, and archaeologists (scientists who study the past through objects) have made exciting finds there.
The plants on the dunes are tough survivors. Only plants that can handle salt, wind and dry sand can grow here - tough grasses with very long roots, and small shrubs that bend in the wind instead of breaking. These plants help hold the dunes in place.
The beach at the base of the dunes faces south, towards Antarctica. The waves here can be much bigger than on Fiji's sheltered north coast, which makes it popular with surfers. Looking out to sea, the next piece of land in that direction is thousands of kilometres away.