Become a Junior Ranger or Young Scientist
If you're traveling with children ages 5 to 12, one of your first priorities when you get to Yellowstone should be to go to the nearest visitor's center and pick up a Junior Ranger kit for each child. For $3, children get a Junior Ranger newspaper full of activities designed to get them involved in exploring and learning about the park.
In the Old Faithful and Canyon areas, children ages 5 and up can also participate in the Young Scientist program. The Young Scientist activities must be completed in one area of the park (either Canyons or Old Faithful), while the Junior Ranger activities can be completed throughout the park.
Try Early-Morning Animal Spotting
Seeing elk, bison, moose and bears close up in the wild is an exciting, memorable experience. To maximize your chances of seeing Yellowstone's animals, especially in summer, it's best to get out on the roads early in the morning when the animals are most active. Look up to see osprey, peregrine falcons, whooping cranes, bald eagles and dozens of other bird species. Look to the water to see beavers, river otters and muskrats. Bring binoculars.
Shop Old Faithful
The Old Faithful area isn't just the home of Yellowstone's most famous geothermal feature; it's also the location of some of the park's biggest and best souvenir shops. Plan to spend an hour or two here looking at kid-enticing doodads.
Enjoy an Old West Cookout
The Old West Dinner Cookout at Roosevelt Lodge offers guests the chance to take a 1- or 2-hour horseback ride or a half-hour covered wagon ride to the dinner site in a large meadow. Guests eat at picnic tables under a canvas roof. There's also cowboy-style entertainment. It's popular, so make reservations well in advance.
Go Horseback Riding
Inside the park, you can reserve a horseback riding adventure through Canyon Lodge, Roosevelt Lodge or Mammoth Hot Springs Hotel. Children must be 8 or older. Try an early morning ride for close-up views of elk and bison. Outside the park in the gateway communities, there are lots of guided trail rides run by local ranchers.
Take in a Ranger Program
At the park entrance you will get a schedule of ranger-guided walks, hikes, campfire programs and stargazing events. These are often informative and entertaining. They're especially nice in the evening, when you might be looking for something to do, since many of the rooms and cabins in Yellowstone don't have TV.
Hit the Boardwalks
Sometimes children aren't especially impressed by Yellowstone's geothermal features, but they will enjoy stomping around on the boardwalks at Upper, Midway and Lower Geyser Basins, Biscuit Basin, Fountain Paint Pots trail and Mammoth Hot Springs. The area kids seem to enjoy the most is Upper Geyser Basin.
Take a Hike
One of the best ways to enjoy Yellowstone's natural beauty is to take one of the hiking trails. One of the most popular is Mount Washburn, a relatively easy climb to the mountain's summit. The trail is 3 miles each way, so unless your children are experienced hikers you probably won't make it to the top. Shorter hikes kids will enjoy include Canyon Rim North, Canyon Rim South, Mystic Falls and Yellowstone River Picnic Area trail.
From its beginning, Yellowstone has been a fisherman's paradise, with literally hundreds of lakes, creeks and rivers. Children under 12 can fish without a permit in Yellowstone, but there's a multitude of regulations governing where, when and how to fish in the park. Check www.nps.gov before your trip, and check with a ranger to find out about seasonal rules.
Swim the Firehole
The Firehole River swimming hole, located on Firehole Canyon Drive, has cool, but not cold, water. It's extremely popular and a lot of fun on Yellowstone's rare hot days. You might see people jumping from the surrounding rocks into the swimming hole. Don't try it. It's dangerous, and if you get caught by a ranger you will have to pay a stiff fine.