Do you like eggs? Do you want to live a long time? According to certain health studies these two inclinations may be at odds. However, thanks to Owakudani’s kuro-tamago you can have your eggs and eat them too.

Located in Hakone, Kanagawa Prefecture, Owakudani translates to “the Great Boiling Valley,” though some locals lovingly refer to it as Jigokudani, meaning “Hell Valley.” Once you visit, you kind of see their point. Owakudani is a volcanic basin created some 3,000 odd years ago after the eruption of Mount Hakone. The resulting crater and subsequent landslides opened up a series of hot springs and sulfur vents that give the entire area a distinctive Dante-ish appearance… and smell.

Incredible Black Eggs of Hakone

The barren, rocky cliffs of Owakudani are eternally shrouded in a sulfuric mist that causes the whole area to smell like eggs that have gone past their expiration date. That and the fact that the caldera’s gurgling waters are being used to boil dozens of eggs.

Kuro-tamago, literally “black eggs,” are regular chicken eggs boiled in Owakudani’s natural hot springs. The sulfur in the water turns the eggshells as black as charcoal. According to local lore, eating one egg will add seven years to your life. You can only buy the black eggs in packs of five for the affordable price of ¥500. This might help explain why Japanese people live longer than everyone else. For the same price as a pint of beer you can add 35 extra years of life.

To witness the eggs being boiled in the hot springs, take a short walk up the mountain from the Owakudani ropeway station. The trek takes about 15 minutes, or roughly one-fifth of the time it takes to cook the eggs. Reportedly, the kuro-tamago are boiled for an hour in the 80-degree hot springs (roughly 175 degrees Fahrenheit), and then steamed for an additional 15 minutes. The eggs themselves taste like regular boiled eggs. They can be purchased directly at the tourist area of the hot springs or at the Owakudani ropeway station.

Walk Through the Valley of the Shadow of Eggs

The valley really has to be experienced firsthand to be appreciated. The problem is, it might not be that easy. Mount Hakone is an active volcano. Due to increased volcanic activity in recent years, some of the hiking trails around the mountain and valley are closed off for everyone’s safety.

In May 2015, even the tourist area was shut down and hasn’t fully opened since. To be clear, the mountain hasn’t erupted in more than 800 years, but it has rumbled due to the flow of hot underground gasses and volcanic matter. In 2015, over 115 quakes were recorded in the area in a single day, which the Japan Meteorological Agency fears might mean that a lava-less eruption of steam is coming. So far, nothing like that has happened, but it’s possible the valley is on borrowed time.

Hakone Ropeway to Hell

It doesn’t mean you shouldn’t visit. Other than the life-prolonging eggs, just traveling to Owakudani is quite a treat. You can get there by car, but taking the Hakone Ropeway is a much more picturesque alternative.

The aerial lift offers amazing views of the tourist center as well as the steaming sulfur vents below, making it look like you’re flying over hell. Although, it is expensive – ¥1,370 one-way to be exact. That’s the price of almost 15 black eggs, or 105 years of additional life. Is it worth it just for the sights? You’ll have to find out for yourself. But be aware the gondolas are sometimes closed due to inclement weather.

For all the comparisons to the underworld, Owakudani valley really is a breathtakingly beautiful place, the egg-like smell vaguely reminiscent of an old gym locker notwithstanding.