Summer Under Glass

Other natural attractions also have survived the tourism assault unscathed. Most notably, the International Crane Foundation has preserved wetlands and grasslands where it raises 15 species of cranes for release into the wild, and the foundation welcomes visitors with an inclination toward nature.

But for decades, Wisconsin Dells has been mostly about manufactured attractions. Over the years, developers wooed tourists with amusement parks, death-defying water ski shows, and, eventually, outdoor water parks. All 18 indoor parks have outdoor sections open in summer. There are three more open to the general public that are outdoors only, including what is arguably America's largest -- Noah's Ark. One of the signature rides there: the Point of No Return, a 10-story slide that shoots riders down in just five seconds.

Problem was, until a few years ago, the tourists disappeared come fall and didn't return until spring.

In 1990, the Dells had a 100-day peak season and an annual hotel occupancy rate of 40 percent. Today, thanks to indoor water parks, the season is 365 days a year. Annual hotel occupancy rates range around 80 percent and routinely hit 100 percent on weekends and school holidays year-round. The area with 5,000 residents now hosts 3 million visitors a year, most of them coming for the water park experience, according to the Wisconsin Dells Visitor and Convention Bureau.

The idea to enclose water parks for year-round use set off one of the hottest trends in hotel and resort development. Five years ago, there were 18 indoor water parks in the United States large and varied enough to legitimately claim the title. Today, there are about 100 in the United States and another 100 or so in Canada, according to the World Waterpark Association. And that's not counting the hundreds of hotels that have expanded and enclosed their pools, added some slides and claimed they have an indoor water park.

Among the 18 indoor water parks in the Dells are three behemoths -- the Kalahari Resort, Great Wolf Lodge and the Wilderness Hotel & Golf Resort. Both the Kalahari and Great Wolf have been busy replicating themselves with somewhat smaller versions. Among the new properties built by Great Wolf is a namesake that opened last spring in Williamsburg.

As I will learn during a two-day tour through the Dells, the three largest water parks -- those that are worth a trip halfway across the country -- all share certain features. No matter which you choose, you are guaranteed multiple swimming pools of various depths. There will be a pool with basketball hoops and volleyball nets, and a pool with floating pads and ropes that kids can hang onto while attempting to walk across the water -- good practice for careers as Marines or Navy SEALs.

All three compete like mad to find new ways to play with millions of gallons of water. They dump it and shoot it and spray it, jet it into geysers and waves, and pump it with the force of fire hydrants to propel you through thrill rides.

The biggest surprise during my visit: Neither the smell of chlorine nor the noise is overwhelming. And although I've arrived at a busy time, I don't feel crowded. These huge domed areas are big enough to absorb people, noise and even the smell of chlorine.

Kalahari

I start my mega-park tour at the Kalahari, which, as the name suggests, has an African theme. In the sprawling lobby under a multi-story ceiling, you can get your picture taken with real live tiger cubs, or buy authentic African art and handicrafts. The place is like an indoor boardwalk, where you can get a caricature drawn, a tattoo or a sugar high from fudge and caramel apples at the Sweet Hut.

The arcade has more than 100 video games. You can sit in rocking chairs to watch first-run films, with wall-to-wall screens and digital surround sound, at the 10-screen movie complex. There are kid-friendly restaurants and a more elegant choice with live entertainment. The day spa is upscale, with peaceful New Age music, and should you have need of a ballroom or conference center, it's got it.

The main attraction, of course, is the water parks, indoor and outdoor.