Next up today, we're turning to WallStreet, a new record set yesterday by the Dow Jones industrial average. The Dow, not the entire stock market, it's a group of 30 major stocks, but it gives an idea of how the entire stock market is doing. Here is a look at the last several years, in 2007, the Dow started dropping, it bottomed down in 2009,then it started going back up. Yesterday when the stock market closed, the Doww as at a new all time high. The Dow was one factor that experts used to figure out how the entire country's economy is doing. The Dow is doing well, the economy is still struggling, what's the deal?

One possible explanation is that investors don't have a lot of opportunities to make money in other way. So the stock market is kind of the best game in town.

At the start of this week, we reported on a sinkhole that formed underneath a house in Florida. Workers have finished tearing down that house and now we can see the actual hole. That's it, about 20 feet wide,more than 50 feet deep. This opened up underneath a bedroom and swallowed one man up. In that's same report in Monday's show, we talked about how and why a lot of sinkholes show up in Florida.This one formed on Monday just three miles away from the first sinkhole. It'snot as big, 12 feet across, four to five feet deep; it's between two houses, so it didn't casue any damage.

David Mattingly had the chance to go in side a sinkhole, this is what found.

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 the sand and dirt.

And if someone were living right on top of this, they'd be at risk.

Yes.

Geologist Jerry Black says Sunshine state home owners might be surprise to find out just how common these are.

Rain waters going to turn into ground water and that's what's naturally acidic, that's the device that dissolves the limestone. And will help create this cavities.

What is unusual about this sinkhole? It's easy to get inside, called the "Devil's Den", it's opened to tourists for viewing and diving. And dive instructor Prince Johnson takes me under for a look. I find that this seemingly placid pool of water is anything but.

The waters has gone down consider ably because of the aquifer, and but it is also risen, when we've had hurricanes and tropical storms, it has risen another 45 feet.

45 feet?

45 feet, so the water is constantly going up and down?

Depending on drought and hurricane.

Down here, it's easy to see how fluctuating groundwater has silently wreak 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. Perhaps most striking to me, how appearances of these sinkholes are so misleading? A single beam of sunlight reveals the cavern is even bigger below the waterline, with tunnels and passageways carved deep into the darkness. But most disturbing could be the view from up top. The round open is deceptively small, little indication of the cavern that's just beneath my feet.

Until a hole like this opens up, there is really no warning, is there?

Correct, it is that random and that sudden,and it could happen obvbiously overnight or at any time.

It can and it does, with thousands of sinkholes opening up in Florida every year.

David Mattingly, CNN, Florida.