The Tottori Sand Dunes (鳥取砂丘 Tottori sakyū) are sand dunes located near the city of Tottori in Tottori Prefecture, Japan. They form the only large dune system (over 30 km²) in Japan.
The dunes were created by sediment deposits carried from the Chūgoku Mountains by the Sendai River into the Sea of Japan. Sea currents and wind help bring the sand from the bottom up onto the shore, where the wind constantly rearranges their shape. The dunes have existed for over 100,000 years, but the area of the dunes has been steadily decreasing due to a government reforestation program following World War II. Additionally, concrete barriers erected to protect the coast (the part of Sanin Kaigan National Park) from tsunamis have disrupted the currents responsible for bringing the sand to shore. Authorities have adopted measures to stop the shrinkage of the dunes, partly because they attract a significant amount of tourism to the area. The Tottori prefectural government has attempted to dump sand off the shore near the dunes in the hopes that it will wash ashore, as well as employing the manual removal of encroaching grassy areas. The lasting ability for these efforts to protect the dunes is as yet unknown. Each year, around two million visitors—mostly from within Japan and East Asia—visit the dunes.