Owakudani, meaning the Great Boiling Valley, is located in the mountain town of Hakone. One can take an aerial tram up to the hot springs, or walk up the 1 km path. On clear days either route delivers spectacular views of the ominous Mt. Fuji.

Once the springs are reached, kuro-tamago, or black eggs, can be purchased four at a time. The eggs are ordinary chicken eggs but the shell turns black due to being boiled in the hot sulfur spring. Local tradition holds that for each black egg eaten, seven years is added to one's life. However, some say that eating more than two is not recommended.

The valley is sometimes referred to as "The Death Valley" by locals. Some 3000 years ago Mount Hakone erupted leaving the hot spring filled crater. All along the path to the egg vendor are active sulfuric geysers, which can be hazardous at times. The area is prone to landslides due to the constant volcanic activity. In potentially unsafe conditions, the walkways to the egg boiling springs may be closed.