Valley of Ten Thousand Smokes Trail

The Valley of Ten Thousand Smokes preserves the largest 20th-century volcanic landscape in North America, produced by the June 1912 Novarupta eruption — the most powerful volcanic eruption of the 1900s. Novarupta ejected more than 3 cubic miles of magma in 60 hours, burying the 40-square-mile Ukak River valley under up to 700 feet of hot pyroclastic material. The valley's name comes from the thousands of fumaroles (volcanic steam vents) observed by botanist Robert Fiske Griggs during his 1916 National Geographic expedition; most fumaroles have since gone cold, but the ash-and-pumice landscape remains strikingly barren and otherworldly. The access trail descends from Overlook Cabin — reached by daily concessioner bus from Brooks Camp across 23 miles of gravel road — into the valley floor, where hikers walk on pale ash deposits cut by deep gorges carved by the Knife Creek and River Lethe. The Lethe Gorge exposes hundreds of feet of compacted volcanic stratigraphy in vivid yellows, oranges, and grays. Wildlife is sparse in the valley but wolves, wolverines, and caribou cross the ash plain seasonally.