Designated as a Special National Natural Monument on December 25, 1954, this is the largest geyser mound group in Japan. Located in the upper reaches of Nakano River originating from Jigokudani (Hell Valley) in Hakusan National Park, positioned in Nakano Valley below Iwama Onsen. Hot spring water erupts and the limestone content in the water precipitates to form bell-shaped travertine towers, some reaching heights of 4 meters. Near 100-degree Celsius hot water vigorously erupts from fumaroles at the tips, creating spectacular steam columns 2-3 meters high. The geyser mounds reach heights of 1.5 meters, resembling giant sake bottles. Vertical stripes of dark green, green, and yellowish-white are visible, created by algae that grow using hot spring minerals as nutrients as the mounds develop. The growth rate of geyser mounds is said to be about 2cm per year. The vivid contrast of white and green creates a precious natural heritage where you can feel the mysteries of the Earth. *Note: The path to the geyser mounds is currently closed and reopening date is undetermined.