Video: A look inside a Sinkhole
By David Mattingly (CNN)-A sinkhole opened up beneath a Tampa, Florida area home last Thursday, and took the life of a man named Jeff Bush.
Now, about three miles away, it's happening again.
The ground opened up between two homes.
There's no damage to either and no relation, except for relative proximity, to the deadly sinkhole.
It's a just few short steps down to an incredible underground sight.
This is the original cavity that eventually collapsed in.
A massive sinkhole carved out of solid limestone by drops of water.
So this is what a sinkhole looks like from the inside?
From the inside, yes. Before you fill it up with sand and dirt.
And if someone were living right on top of this, they'd be at risk?
Geologist Jerry Black says sunshine state homeowners might be surprised to find out just how common these are.
What are the chances of someone having a house in central Florida and living on top of something like this?
Very good. Probably not one as close to the surface as this but you definitely have cavities of this size all over the state of Florida.
Fossils found in this sinkhole show it has been around since the ice age, but no different black says than the sinkholes we see opening up today.
These are just a few of his pictures.
The one thing they all have in common is water.
Rainwater is going to turn into groundwater and that's what's naturally acidic, that's the device that dissolves the limestone and will help create these cavities.
What is unusual about this sinkhole, it's easy to get inside.
Called the Devil's Den, it's open to tourists for viewing and diving.
And dive instructor prince Johnston takes me under for a look.
I find that this seemingly placid pool of water is anything but.
The water has gone down considerable because of the aquifer but it's also risen. When we've had hurricanes and tropical storms it's risen another 45 feet.
So the water's constantly going up and down in here?
Up and down.
Depending on droughts and hurricanes.
Down here, it's easy to see how fluctuating ground water has silently wreaked havoc.
I pass by limestone boulders as big as cars sitting on the bottom.
And these same forces are still at work, compounded by the demand for fresh water.
It's progressively dropping yearly and that's basically over the whole state of Florida. The aquifer is getting lower and lower.
Perhaps most striking to me, how appearances of this sinkhole are so misleading.
A single beam of sunlight reveals the cavern is even bigger below the water line, with tunnels and passageways carved deep into the darkness.
But most disturbing could be the view from up top.
The round opening is deceptively small, little indication of the cavern that's just beneath my feet.
Until a hole like this opens up, there's really no warning is there?
Correct. It is that random and that sudden and it can happen obviously overnight or at anytime.
It can and it does, with thousands of sinkholes opening up in Florida every year.