This episode begins in Estero Bay.

Florida's geology, it's sandy surface soil, abundance of surface water and ground water, and limestone karst bedrock make it the sinkhole capital of America. Ann Tihansky studied sinkholes for many years in Florida with the U.S. Geologic Survey and put together the "Sinkholes 101" guidebook. She joins us to explain why and how sinkholes form.

Graphic of water distribution on, in and above the earth. Another one.

How much water there is on earth.

New York Times article on America's sinking East Coast.