A sinkhole is a depression or hole in the ground caused by the collapse of a surface layer. They often occur in areas where the underlying rock, such as limestone, is dissolved by water, creating underground cavities. When the ground above can no longer support its weight, it collapses, forming a sinkhole. Sinkholes can vary in size, from a few feet to hundreds of feet across. They can develop suddenly or gradually over time. Factors like heavy rainfall, drought, or human activities, such as drilling or mining, can increase the likelihood of sinkhole formation.