Upper Geyser Basin Trail

The 2.1-mile, flat Upper Geyser Basin Trail begins left of Old Faithful at a trail junction by the Old Faithful Inn, front parking lot. From here, it does a 0.6-mile, clockwise loop around Old Faithful Geyser, passing the starting point and continuing along the paved path for 0.4 miles to Castle Geyser. The trail turns right, following boardwalks past Crested Pool, crosses the Firehole River, and reaches a junction near Sawmill Geyser 0.2 miles from Castle. At the junction, the trail turns left and continues past numerous features, including Grand Geyser, Economic Geyser, and Beauty Pool, before crossing back over the Firehole 0.4 miles from Sawmill. The trail continues another 0.3 miles, past Giant Geyser and reaches Grotto Geyser. From Grotto, the trail turns left, then immediately right, for its last leg passing Daisy, Comet, and Splendid Geysers before ending at its junction with the Punch Bowl-Black Sand Basin Trail. Check the Visitor's Center for eruption times for Old Faithful, Castle, and Grand geysers before starting. The following are important features you'll see along the trail: Castle Geyser has the largest cone and may be the oldest geyser in Yellowstone. Since geyserite cones build up at only 1 to 2 inches every 100 years, we know that Castle is quite old. It erupts every 10-12 hours. Eruptions frequently reach 90 feet and last about 20 minutes. The water phase is followed by a noisy steam phase lasting 30-40 minutes. Members of the 1879 Washburn Expedition named Castle Geyser for its resemblance to the ruins of a feudal castle. Grand Geyser, the tallest predictable geyser in the world, erupts every 7-15 hours. A classic fountain geyser, Grand erupts from a large pool with powerful bursts rather than a steady column like Old Faithful. An average eruption lasts 9-12 minutes and consists of 1-4 bursts, sometimes reaching 200 feet. Giant Geyser was dormant for many years after 1955. Since then, it has slowly become active. In 1997, eruptions occurred every 3-10 days. Eruptions last about an hour and can reach heights of 180-250 feet. Today eruptions are less frequent. Grotto Geyser erupts about every eight hours splashing 10 feet. The weirdly shaped cone that gives the geyser its name is from geyserite covering the trunks of trees that once grew here. Daisy Geyser erupts at an angle to a height of 75 feet for 3-5 minutes. Daisy is quite predictable, with eruption intervals of 110-240 minutes. Thanks to guidebook author, Tom Carter, for sharing this trail description. To learn more about visiting Yellowstone, check out his book, Day Hiking Yellowstone.