Many sinkholes are small and shallow, like puddles. But some can grow large enough to swallow up cars—and even entire buildings.
These pits form when water eats away at rock beneath the ground. Some types of rock, such as limestone, break down easily. Running water can make limestone holey, like Swiss cheese. Over hundreds—sometimes thousands!—of years, these underground holes become large enough that the ground’s surface grows weak and starts to cave in.
Sinkholes can open up suddenly, without warning. But let this sink in: Sinkholes that appear suddenly are rare. The chance of falling into one of these cavities is very slim.