They're known as "geological time bombs," affecting about 20% of the country.

Now a Discovery Channel special on Destination America takes a closer look at the problem of sinkholes and calls Florida "ground zero."

"Sinkholes: Swallowed Alive" features two recent Florida sinkholes, including the one at Clermont's Summer Bay Resort.Last August the huge hole opened, swallowing one of the resort's three story buildings. Sky 6 flew over the site earlier Tuesday, showing the hole is filled and the surrounding buildings are reopened.

In April of last year, a sinkhole killed Seffner man Jeff Busch as he lounged in his bedroom.

Destination America General Manager Marc Etkind calls the special "a fascinating look at a very real hazard we see in the news more and more, proving nobody's safe."

You can catch the one-hour special Wednesday at 9 p.m. Eastern time.