Distance: 5 miles round-trip
Duration: 2-3 hours
Elevation: 7,600 feet
Trailhead: Lone Star Geyser Trailhead 3.5 miles south of Old Faithful Junction (just east of Kepler Cascades)
A wide paved trail (actually an old road) leads to this popular geyser. It’s a favorite of bicyclists in the summer and skiers in the winter. Lone Star Geyser erupts every three hours from a distinctive nine-foot-high cone, with eruptions generally reaching 45 feet and lasting for 30 minutes. Bikes are not allowed beyond the geyser. Hikers can also get to Lone Star via the Howard Eaton Trail out of Old Faithful  (6 miles round-trip). For a longer hike, you can continue south from Lone Star on Shoshone Lake Trail to Shoshone Lake, eight fairly easy miles from the main road.
Distance: 2.5 miles round-trip
Duration: 1 hour
Elevation: 7,100 feet
Trailhead: at the back of the Biscuit Basin boardwalk (2 miles north of Old Faithful Junction)
This path follows a pretty creek to where the Little Firehole River cascades 70 feet over Mystic Falls. You can switchback farther up the trail to the top of the falls and then connect with another trail for the loop back to Biscuit Basin (3 miles round-trip). This is a very nice short hike and can be lengthened into a trip to Little Firehole Meadows (10 miles round-trip), where bison are often seen in the summer.
Distance: 5 miles round-trip to Fairy Falls
Duration: 2 hours
Elevation: 7,250 feet
Trailhead: 1 mile south of Midway Geyser Basin  (4.5 miles north of the Old Faithful Interchange)
The four-mile-long Fountain Freight Road is closed to cars, but it’s a great place for mountain bikers and those out for a relatively level walk. A steel bridge crosses the Firehole River at the southern trailhead, and the road soon passes the west side of spectacular Grand Prismatic Spring; rough trails lead up the hillside for a better view. One mile up from the trailhead you’ll come to Fairy Falls Trail on your left. It’s an easy walk to the falls, a 200-foot ribbon of water cascading into a large pool. The hike to Fairy Falls can be combined with longer treks to Little Firehole Meadow and Mystic Falls or to a pair of small peaks called Twin Buttes.
Half a mile beyond Fairy Falls is Imperial Geyser, with periodic small eruptions. Nearby Spray Geyser erupts frequently, sending water six feet in the air. For a longer version of the hike to Fairy Falls (10 miles round-trip), start from the north end, where Fountain Flat Drive ends. The Fairy Falls area is closed mid-March-May due to bear activity.