The financial crisis gave us a term few had heard before in relation to mortgages: underwater, the unenviable state of owing more on your loan than the home is worth. Well, the term is still with us, and will be for a while, though it gradually applies to fewer and fewer borrowers.

"As home values continue to rise, the national negative equity rate continued to fall in the second quarter, dropping to 23.8% of all homeowners with a mortgage," says Zillow.com, the home-sale and mortgage-information company.

But there's bad news too:

"Millions of homeowners remain so far underwater that it will take years for them to regain equity, even as home values continue their recovery."

Though lots of attention has been paid to rising home prices, it will take much bigger gains to get many of today's underwater borrowers above water. And, unfortunately, many experts think the pace of gains, torrid in many markets over the past year or so, will slow down.

About 12.2 million homeowners were underwater at the end of June, compared with 15.3 million a year earlier, Zillow says.

For an even more realistic and disturbing view, Zillow calculates an "effective" underwater figure that includes homeowners who are above water but have equity, of less than 20% of the home's value — owing more than $80,000 on a $100,000 home, for instance. It's difficult for these owners to sell because the proceeds may be insufficient to cover the down payment and closing costs on the next home.

The effective negative equity rate was 41.9% at the end of June, down just a tad from 43.6% at the end of March. That's a huge number of people trapped in their homes, unable to move for a new job and making payments on a property that's worth less than they'd bargained for when they took out the loan.

The hardest-hit markets are Las Vegas, with an effective underwater rate of 66.9%, Atlanta at 61.3%, and Riverside, a Los Angeles suburb, at 56.1%

"Widespread rising home values during the past year have helped chip away at negative equity nationwide, helping many homeowners who were only modestly underwater to come up for air," Zillow Chief Economist Dr. Stan Humphries says.

"For those homeowners who are deeply underwater, though, there is still a long row to hoe," Humphries says. "The frustratingly slow pace of negative equity declines in the face of such robust home value appreciation is a direct result of the fact that many people in the hardest-hit markets are underwater by an enormous amount."

It will take years for those markets to return to normal, he says. If home price appreciation settles down to 3% or 4% a year, as many experts expect, it could take five to 10 years for a deeply underwater homeowner to get above water.

Fortunately, some of the markets hit hardest by the home price collapse also have the quickest rebounds. Homeowners also reduce debt gradually through their regular monthly payments. Use the Mortgage Loan Calculator to see how quickly your debt will shrink.