Ōwakudani

Owakudani is a volcanic valley in Hakone, Kanagawa Prefecture, Japan, whose name translates to "Great Boiling Valley." It formed about 3,000 years ago when an explosive eruption of the Hakone volcano tore open the landscape, and its active sulfur vents and hot springs remain a direct legacy of that eruption. Mineral-rich, sulfur-heavy geothermal water still surfaces across the valley, hot enough that it is used commercially to boil eggs, whose shells turn black from the mineral content. Present-day activity around the vents follows massive landslides that reshaped the valley after its formation, and the unstable ground is now held in place with concrete barriers. The site remains volcanically active enough that it was closed to visitors from May 2015 due to elevated hazard levels, reopening with restricted access in April 2016, and people with respiratory or heart conditions are advised against entering because of the volcanic gases. This entity documents Owakudani specifically as a geological formation, a volcanic valley opened by an eruption of the Hakone volcano about 3,000 years ago.