Owakudani or “the Great Boiling Valley” in Hakone, Japan, is hardly the ideal tourist spot. It’s a large volcanic caldera formed around 3,000 years ago following a large eruption of Mount Hakone. Owakudani is still active with boiling pools of sulphur-rich water and huge vents spewing forth steam and volcanic fumes of hydrogen sulphide and sulphur dioxide. The entire area has a strong smell of rotten eggs, but it’s the eggs the tourists who visit the Great Boiling Valley are seeking for.

The Owakudani black eggs or “Kuro-tamago” are regular chicken eggs that are hard-boiled in the naturally hot water pools. The sulphur in the water renders the eggs’ shell black while also imparting a peculiar smell to it. Locals say that taking one can prolong one’s life by seven years. Take two, and you’ll get 14 extra years added to your life.

Photo credit: Maryline P/Flickr