Natural sinkholes are depressions or holes in the ground caused by the collapse of a surface layer. They often form in areas where the underlying rock, such as limestone, is dissolved by water, creating underground cavities. When these cavities become too large to support the ground above, the surface can suddenly collapse, resulting in a sinkhole. These geological features can vary in size, from small puddles to large craters. Sinkholes are commonly found in regions with karst topography, where the landscape is shaped by the dissolution of soluble rocks. They can pose risks to infrastructure and ecosystems, making them important to study and monitor.