Owakudani is a remarkable volcanic area in Hakone, Kanagawa Prefecture. Formed by volcanic landslides, it is characterized by active geothermal activity and numerous steaming vents. Located on the northern slope of Mount Kanmurigatake, at elevations of approximately 800 to 1,000 meters, it is the largest fumarolic area in the Hakone volcanic region. The landscape is strikingly different from the green forests and tranquil lakes often associated with Hakone. Sulfurous odors drift through the air, while white steam rises from the ground, creating an impressive scene that reveals the power of the Earth’s volcanic forces. Owakudani also plays an important role in the area’s hot spring industry. Natural volcanic steam and groundwater are used to produce hot spring water, which is supplied to many accommodation facilities in Hakone.
The formation of Owakudani began approximately 3,100 years ago, when a phreatic explosion occurred at Mount Kamiyama, the highest peak in the Hakone volcanic complex. The explosion caused a large landslide, and the resulting debris accumulated across the surrounding area. Approximately 2,900 years ago, a relatively small pyroclastic flow occurred, giving rise to Mount Kanmurigatake. Volcanic deposits accumulated during these events and helped shape the landscape that can be seen today. Beneath the area extending from Owakudani toward Gora are several funnel-shaped caldera structures. These underground formations are known collectively as the Gora Subsurface Caldera Structure.
Volcanic activity around Owakudani has been recorded over many centuries. Three episodes of volcanic material falling from the atmosphere were recorded between the 12th and 13th centuries. In 1910, a debris flow near Chiikezawa claimed six lives. In 1933, increased fumarolic activity caused the location of the vents to shift, resulting in one fatality. Other notable events include a landslide in 1948 and changes in the location of the fumarolic zone between 1974 and 1978. These events illustrate that Owakudani is an active volcanic environment whose landscape and geothermal features can change over time.
Volcanic activity continued to be observed at Owakudani after the year 2000. In 2001, a steam well at Owakudani experienced a violent eruption of steam. In 2002, part of the eastern slope of Mount Kanmurigatake collapsed, triggering a debris flow.
In 2015, the number of volcanic earthquakes increased, and on May 6 the volcanic alert level was raised to Level 2, indicating restrictions around the crater area. Access to parts of the surrounding area was restricted. On June 29, volcanic ash was confirmed to have fallen, and in July a new crater was identified. During this period, the volcanic alert level was raised to Level 3. From around late August, seismic activity gradually subsided, and the alert level was lowered to Level 2 in September. Volcanic activity subsequently continued to settle, and the Hakone Ropeway resumed operations in 2016.
During the Edo period, Owakudani was known as Jigokudani, meaning “Valley of Hell,” or Daijigoku, meaning “Great Hell.” These names reflected the area’s barren landscape, sulfurous odors, and clouds of volcanic steam. In 1873, when Emperor Meiji and Empress Shoken visited the area, its name was changed to Owakudani. In 1970, a schoolchild on a school excursion was killed in a rockfall accident. Following this incident, greater emphasis was placed on visitor safety. In 1983, the area was developed as the Owakudani Park within Fuji-Hakone-Izu National Park. Improvements to visitor facilities and access, including the Hakone Ropeway, helped establish Owakudani as one of Hakone’s major sightseeing destinations.
One of Owakudani’s best-known specialties is its black eggs, called *kuro-tamago*. These eggs are cooked using the area’s geothermal hot water and have shells that turn black through a chemical reaction involving sulfur and iron in the hot spring water. According to a local saying, eating one black egg adds seven years to your life. The eggs have become a popular specialty and souvenir for visitors to Hakone.
The Hakone Geo Museum opened in 2014 and introduces visitors to the geological history and volcanic activity of the Hakone area. Its exhibits help explain how the Hakone volcano was formed and how its landscape has changed over time. Visitors can also learn about the area’s distinctive natural environment, including *Iou-goke*, a type of lichen associated with sulfur-rich volcanic surroundings. The museum offers an opportunity to understand the scientific background of the landscape before or after exploring the geothermal area itself.
On the northern side of Mount Kamiyama is Owakudani Park, which includes the approximately 600-meter circular Owakudani Nature Research Trail. The trail provides visitors with an opportunity to explore the volcanic environment at close range. It passes through an area where geothermal activity can be observed, allowing visitors to experience the unusual landscape of steaming vents and volcanic deposits. Access to the park and trail has been restricted at various times because of volcanic activity. Parts of the area have reopened after safety measures were introduced, but access conditions can change depending on the situation. Visitors should always follow current restrictions and instructions from the authorities and park management.
The fumarolic area of Owakudani accounts for approximately 26.3 percent of the total heat released by the Hakone volcanic system. In addition to natural steam vents, more than 30 drilled wells are used in the area. Hot spring water is produced by mixing geothermal steam from these wells with groundwater. Artificial vents may also be drilled as part of efforts to reduce the pressure and amount of steam released from other fumaroles. These geothermal resources are important to Hakone’s hot spring industry, supplying water to many inns and hotels in the region.
Gases released from Owakudani include water vapor (H2O), hydrogen sulfide (H2S), carbon dioxide (CO2), and sulfur dioxide (SO2). Approximately 98 percent of the gas mixture consists of water vapor. Although the rising steam creates a spectacular sight, volcanic gases can affect both the surrounding environment and human health. Hydrogen sulfide and other volcanic gases may be hazardous, particularly for people with respiratory or heart conditions. Visitors should pay attention to warning signs, observe any access restrictions, and follow the instructions of staff and local authorities. If conditions change, parts of the area may be closed for safety reasons.
As part of the Hakone volcanic system, Owakudani is expected to remain subject to volcanic activity in the future. Maintaining its appeal as a sightseeing destination while strengthening disaster-prevention and visitor-safety measures is therefore essential. The area is also an important place for learning about geology, volcanic processes, and the natural history of Hakone. Its dramatic scenery and scientific significance make it a destination where visitors can experience the power of nature while gaining a deeper understanding of Japan’s volcanic landscape.
Owakudani offers a rare opportunity to see the geothermal activity of a volcano at close range. Rising steam, sulfurous scents, unusual rock formations, and sweeping mountain views create a landscape unlike the more familiar scenery of Hakone. Visitors can explore the nature trail when it is open, learn about the area’s geological history at the Hakone Geo Museum, and try the famous black eggs. The experience provides a memorable insight into the natural forces that have shaped the Hakone region.
9:00-17:00
No holidays
Public Transportation: 40 minutes from Hakone-Yumoto Station to Gora Station on the Hakone Tozan Railway Line → 10 minutes from Gora Station to Owakudani Station on the Hakone Tozan Cable Car, 10 minutes from Hayakumoyama Station to Owakudani Station on the Hakone Ropeway, a short walk
By car: Approx. 45 min. from Gotemba IC on Tomei Expressway