By Lisa Rogak

Kentucky's Mammoth Cave National Park boasts the longest cave system in the world.

For many families, a trip to a national park is as important as that first trip to Disney World: It's a significant rite of passage for parents and children. While Yellowstone and the Grand Canyon are must-sees, there are a number of lesser known parks across the country with fewer crowds and more adventurous activities. You can all spend a week on a houseboat in northern Minnesota, or your kids can explore a network of Kentucky caves on a no-parents-allowed journey. But before you plan a park trip, it's important to make sure everyone will be happy.

The Right Fit

"The most important thing parents can do is pick a park with activities appropriate for every family member," says Kurt Repanshek, author of Frommer's National Parks with Kids. "Parents need to be sure they don't settle on a park where the activities like climbing, rafting or even hiking, are more challenging than their kids can handle," he says. "Most parks offer a wide range of activities, so a family with children of different ages could split up for a day or two with mom and some kids going in one direction and dad and the other kids in another."

For example, at Yosemite a teenager might like the challenge of a climbing school while a younger child would prefer an easy hike around a lake. At Acadia, a teen can learn to sea kayak, and a younger child could ride a bike on the carriage paths or paddle a canoe on Long Pond. Your biggest problem may be finding there's too much to do, especially with the Junior Ranger programs which are similar to a scouting merit badge program. Upon arrival, each child receives a booklet with a list of activities, ranging from a scavenger hunt to a park ranger-led nature walk. When the child completes the list, the ranger presents him or her with a badge.

Kids can get a head start before they leave home by signing up for the online WebRangers program where they can play games, decode secret messages and learn about the different badges they can earn.

No matter which park you choose, Repanshek says the best way is to pace the trip for the entire family. "National parks are not designed to be enjoyed on the fly," he says. "Don't over-schedule your vacation by trying to squeeze as many sights and activities as possible into it, and don't be afraid to say, 'We'll come back next year.' "

Read more about each park that made our list or see entire slide show:

Acadia National Park
Mammoth Cave
Grand Canyon
Great Smoky Mountains
Olympic
Voyageurs
Yellowstone
Yosemite