The most dramatic landscape in the Hakone area: a raw volcanic valley still belching sulphurous steam from dozens of vents, the aftermath of Mount Hakone's last major eruption around 3,000 years ago. The name means 'Great Boiling Valley'. The ropeway passes directly over it and the view from the gondola is genuinely striking.
At the valley station, vendors sell kuro tamago — black eggs boiled in the mineral springs, their shells stained dark by hydrogen sulphide. The eggs themselves taste like normal hard-boiled eggs; the legend that each one extends your life by seven years is unverified. There is a short walking trail through the steam vents; the smell of sulphur is strong. On clear days Mount Fuji is visible from the observation area.