Some of the world's most famous sinkholes are seemingly endless pits that swallow trees, cars and entire buildings — dangerously altering the landscape. Others fill with water, becoming popular swimming holes and offering unique photo opportunities.
In the strictly geological sense, sinkholes occur when water erodes solid bedrock, creating an underground cavity that collapses inward. However, the term can be used in a broader sense to describe any sudden slump of the Earth's surface. Regardless of how you define them, these massive holes capture our curiosity with the mysteries of their bottomless depths.