Owakudani: The Smoking Valley of Wonders I discovered in Japan

Hakone (Japan): During my recent tour of Japan, one place that left an unforgettable mark on me was Owakudani, the “Great Boiling Valley.”

Nestled in the volcanic mountains of Hakone, about 100 kilometres from Tokyo, this dramatic landscape is unlike anywhere else I have seen — a place where nature seems alive, breathing steam and mystery with every gust of wind.

As I approached the valley, the air turned thick with the sharp scent of sulphur, and pillars of white smoke rose from the ground like something out of a fantasy film. The scenery was surreal — part science fiction, part sacred legend.

Yet amid the rugged terrain and geothermal energy, one simple thing captured everyone’s attention: the black egg, or kurotamago.

A place of fire, faith, and fascination

Formed nearly 3,000 years ago by the eruption of Mount Hakone, Owakudani remains one of Japan’s most active geothermal zones. The locals call it Jigokudani, meaning “Valley of Hell,” but standing there, surrounded by clouds of steam and the distant outline of Mount Fuji, I found it breathtaking — more a valley of wonder than of fear.

What truly intrigued me was the deep connection between the valley’s fiery nature and its ancient beliefs. In the midst of this steaming landscape stands the statue of Enmei Jizo, carved more than 1,200 years ago by the monk Kobo Daishi.

Jizo, known as the guardian of children and the symbol of longevity, is believed to bless the waters of Owakudani. Over generations, people began to believe that eggs boiled in these sacred springs could carry his blessings — extending life by seven years for each one eaten.

The secret of the black egg

As I learned during my visit, there’s fascinating science behind the legend. Ordinary eggs are placed into the valley’s bubbling sulphur hot springs, where the water — rich in iron and minerals — reacts with the calcium in the eggshells.

The result is a perfectly natural transformation: the shells turn black while the inside remains unchanged.

I bought a pack of kurotamago from the OwakudaniKurotamagokan shop, still warm from the morning’s volcanic bath.

Sitting on a wooden bench, with sulphur clouds drifting nearby and Fuji’s snow-capped peak in the distance, I cracked open one of the eggs.

It looked ordinary inside, but the moment felt extraordinary. Whether or not I truly gained seven extra years, I felt that my time in Owakudani had already added something special to my life.

A valley that breathes — and warns

Nature here is powerful and unpredictable. In May 2015, the valley was temporarily closed due to heightened volcanic activity and dangerous gas levels. It reopened partially in April 2016, but visitors are still restricted from going too close to the steaming vents. Signs warn of potential health hazards, and people with asthma, bronchitis, heart conditions, pacemakers, or pregnant women are advised to avoid the area because of the strong volcanic gases.

Even with these cautions, the area feels safe and well-managed. Standing at the observation decks, you can watch the earth breathe — a rare and humbling experience that reminds you of the forces beneath our feet.

An unforgettable journey above the steam

One of the best ways to experience Owakudani is by taking the Hakone Ropeway. As I glided silently over the valley, I looked down on the smoking earth below and out toward Mount Fuji’s majestic silhouette. The view was pure magic — an ever-changing mix of mist, light, and colour.

At the ropeway station, tourists queued up for black eggs, ice cream, and volcanic souvenirs, laughing and taking photos against the backdrop of swirling steam.

The atmosphere was warm, lively, and distinctly Japanese — a perfect balance of reverence for nature and joyful curiosity.

A living legend in the heart of Japan

My visit to Owakudani was more than just sightseeing — it was a journey into Japan’s living geology and spiritual heritage. This valley, where myth meets science, embodies the country’s deep respect for the natural world.

As I left Hakone, the smell of sulphur still lingering faintly in my jacket, I carried with me more than just memories of a breathtaking landscape. Owakudani had shown me that even in the harshest environments, life — and legend — find a way to coexist beautifully.

Whether or not the black egg truly adds seven years to one’s life, one thing is certain: my time in Owakudani will stay with me for many years to come.