Boiling River: The hike is a simple one-mile out-and-back trail with easy terrain. As such, the entire family can take part. At the end of the trail, you'll find boiling geysers feeding into the cold Gardiner River; the result is hot tub-like waters that you can soak in. There are several regulations and time constraints on the use of this attraction so check conditions at NPS.gov before you go.
Trailhead: located just south of the Gardiner entrance
Upper Geyser Basin: This is one of the most popular Yellowstone hikes because it offers ample opportunity to witness geothermal activity. It also has multiple looping trails that allow you to alter the length of your trip, ranging anywhere from 0.25 to 5 miles. Look for attractions such as Old Faithful, Morning Glory Pool, Grand Geyser and Castle Geysers.
Trailhead: Old Faithful Visitor Center
View from the Upper Geyser Basin
Tower Fall: Yellowstone is home to more than 40 major waterfalls, but Tower Fall stands out. The short hike, one-mile round trip, rewards you with unforgettable views of the 132-foot waterfall.
Trailhead: the Tower Fall store
Seven Mile Hole: This hike takes you from the rim of the Grand Canyon of Yellowstone down to the river below. As such, it's a challenging course: Start on a downhill and end with a strenuous uphill trek. Along the way, enjoy the majesty of the canyon's brilliant colors and fascinating geothermal areas. From the suggested trailhead, the hike is 9.8 miles in total.
Trailhead: Glacier Boulder Trailhead
Camp near Yellowstone: Threemile Campground