The spring water at this site is acidic enough to potentially dissolve a steel nail within a few days.
The water discharge volume at the O-buki fountainhead is recorded at 9,000 liters per minute, ranking it as one of the largest single-source hot springs in Japan.
The site contains Hokutolite, a rare radioactive mineral formed by the precipitation of quartz and lead-rich barite from the hot spring water, which is protected as a special natural monument.
Some visitors practice 'ganbanyoku' (bedrock bathing) by lying on the warm, geothermal-heated stones along the trail, a practice historically linked to therapeutic beliefs.
The high sulfur content creates a yellowish, crystalline landscape that lacks typical forest undergrowth.
The Tamagawa Onsen Nature Research Road is a boardwalk trail located in the Towada-Hachimantai National Park, characterized by its proximity to highly acidic volcanic vents and geothermal springs. The area is famous for the Tamagawa Onsen spring, which produces the most acidic water in Japan, featuring a pH of approximately 1.2. The trail winds through the 'O-buki' area, where massive volumes of geothermal water reach temperatures of 98 degrees Celsius. Visitors can observe bubbling mud pots, steam vents, and yellow sulfur deposits that coat the rugged, rocky terrain. The trail provides direct access to the volcanic landscape surrounding the source of the Tamagawa hot spring waters. Natural geothermal phenomena are highly active, creating a distinct, harsh landscape where vegetation is sparse due to high sulfur concentration.
The O-buki main vent area where large volumes of water and steam emerge from the rock face.
Wear sturdy, closed-toe walking shoes as the rocky path is uneven and hot sulfur steam can be corrosive.
Bring a towel if you intend to experience the natural bedrock-heated areas near the trail.
Protect camera equipment and electronics, as the hydrogen sulfide gas can corrode metal parts over time.
Avoid touching the water or mud directly, as the extreme acidity can cause skin irritation.
Closed during the winter season due to heavy snowfall; access is restricted once snow clearing operations cease.
Do not wander off the marked boardwalks, as the ground in some areas is unstable and the heat can be dangerous.
