Formed by a phreatic (steam) eruption of Mount Hakone roughly 3,000 years ago, Owakudani is a still-active volcanic valley where sulfurous steam vents rise from cracked ground across the site. Eggs boiled in the local hot spring water turn black as sulfur and iron react with the shell, giving rise to the famous claim that eating one adds seven years to your life. On clear days, the ropeway's summit station offers views of both Mount Fuji and the volcanic crater. When volcanic gas levels rise, authorities issue advisories and can temporarily restrict ropeway service or trail access.
