Mambrui Sand Dunes are a natural wonder and tourist attraction in Kenya. The sand dunes are a threat to the nearby town of Mambrui, which was built by Arab slave traders in the 15th century. The town is a destination for Islamic pilgrims and is home to Quran schools. However, a 1997 UNESCO–Kenya National Seminar paper on Sustainable Coastal Development warned that the town would soon be covered by the sand dunes and no longer exist.
Dunes are mounds of sand that form when wind blows sand into a sheltered area, such as behind an obstacle. As grains of sand accumulate, the dunes grow.