Okususo Nature Garden is a beautiful natural park in the Kinasa area of Nagano City, located in the upper reaches of the Susobana River. At an elevation of approximately 1,200 meters, the area is surrounded by extensive beech forests and is known for its wetlands, ponds, and pristine mountain scenery.
Located deep in the mountains of northern Nagano, Okususo offers visitors a peaceful escape into nature. Its remote atmosphere, rich forests, wetlands, and distinctive geological formations make it one of the region’s most fascinating destinations for nature lovers and hikers.
The greatest attraction of Okususo Nature Garden is its enormous colony of mizubasho, or Asian skunk cabbage. Around 810,000 plants grow naturally throughout the garden, forming one of the largest concentrations of mizubasho on Honshu.
Ponds and wetlands are scattered throughout the area, including Hyotan Pond, Yoshi Pond, Ima Pond, and Koumidaira Wetland. In spring, the delicate white flowers of the mizubasho emerge as the snow melts, creating a striking contrast against the dark forests and remaining patches of snow.
The blooming season is celebrated as a symbol of the arrival of late spring in northern Shinshu. The scenery has also been recognized among Japan’s notable hidden natural destinations, attracting nature enthusiasts, hikers, and photographers from across the country.
Okususo Nature Garden is generally open from late April through late October, allowing visitors to experience the landscape in several different seasons.
Mid-May is especially popular, when the mizubasho are usually at their best and fresh green leaves begin to emerge throughout the beech forests. By autumn, the forest is transformed by brilliant foliage, creating another spectacular setting for walking and photography.
Each season brings a different atmosphere, from spring flowers and fresh greenery to the colorful forests of autumn and the quiet mountain landscape beyond.
A network of walking trails allows visitors to explore the ponds, wetlands, forests, and mountain scenery on foot. Depending on the route, visitors can enjoy approximately two to four hours of light hiking or trekking.
One popular route begins at the Visitor Center and continues via the rest area and Benten Island to Yoshi Pond and Koumidaira Wetland. The complete route takes approximately two hours.
The trail passes through a series of ponds and wetlands while offering close views of mizubasho and the surrounding beech forest. The paths are relatively well maintained and can be enjoyed by visitors without extensive hiking experience.
However, significant amounts of snow may remain during the mizubasho season in early May. Visitors should therefore wear sturdy footwear with good traction and be prepared for wet or slippery conditions.
Okususo Nature Garden is approximately 40 kilometers from Nagano Station. During the operating season, visitors using public transportation can take Alpico Kotsu’s seasonal Express Okususo Line from Nagano Station.
The journey to the Okususo Nature Garden entrance takes approximately two hours. From the bus stop, the garden entrance can be reached in about 20 minutes on foot, or approximately five minutes by shuttle bus when shuttle services are operating.
By car, the journey from Nagano Station takes approximately 80 minutes. From the parking area, the garden entrance is about a 30-minute walk. When shuttle buses are operating, the journey from the parking area to the entrance takes approximately 10 minutes.
The garden generally opens from late April through late October. Opening hours are approximately 8:30 a.m. to 5:00 p.m., with admission until 4:00 p.m.
Admission is 410 yen for visitors of junior high school age and older through the end of May, and 200 yen from June onward. Children of elementary school age and younger can enter free of charge.
Beyond the nature garden lies Okususo Gorge, a spectacular valley in the upper reaches of the Susobana River. The gorge extends for approximately 5 kilometers upstream from Okususo Dam, revealing dramatic cliffs, folded rock layers, and other geological formations shaped by erosion over long periods of time.
Some cliffs of folded mudstone and sandstone reach approximately 100 meters in height. During the autumn foliage season, red and golden trees reflected in the reservoir create an especially impressive landscape.
The gorge has been recognized among Japan’s scenic natural landscapes and is particularly popular as an autumn destination for visitors interested in dramatic mountain scenery.
The area around Okususo Gorge is characterized by relatively fragile geological formations consisting of mudstone, sandstone, and tuff. Over time, erosion by the Susobana River has produced a remarkable collection of geological features.
Visitors can find unusual rock formations, strongly folded strata, cuesta landforms, potholes, sandpipes, and ripple marks preserved in the rocks. Together, these features offer a fascinating glimpse into the geological history of the region.
Kisoden Abuki is a large natural rock shelter approximately 60 meters wide and 20 meters deep. It is believed to have once been considerably larger. According to local tradition, the name is associated with the legendary warrior Kiso Yoshinaka, who is said to have camped in the area.
Another striking feature is the honeycomb weathering found in the rocks around Genmu Cave. Wind erosion has created countless small cavities across the rock surface, giving it an appearance similar to a giant honeycomb.
Similar formations along Fukayazawa, a tributary of the Susobana River, have been designated as a Natural Monument of Nagano Prefecture.
The gorge also contains unusual landforms such as Chisen Senjojiki, cuesta formations, and potholes. These features were created through the combined effects of geological folding and long-term erosion, making the area particularly interesting for visitors fascinated by geology and natural landscapes.
The sandstone and mudstone in this region can become weakened when saturated with water. As a result, landslides are particularly likely during the snowmelt season.
In 1997, a major landslide occurred in the upper reaches of the Nigorigawa River. The debris formed a natural dam approximately 60 to 70 meters high, demonstrating the powerful geological forces that continue to shape the Okususo landscape.
These natural hazards are also an important part of understanding the geological character of the region and the constantly changing relationship between water, rock, snow, and mountain terrain.
The Susobana River flows through the Okususo Nature Garden and Okususo Gorge before continuing toward central Nagano City. The clear mountain river is an important part of the area’s landscape.
Okususo Dam lies along the river and serves important roles in water resources and disaster prevention. Surrounded by mountains and forest, the dam and its reservoir also form an attractive scenic landscape, particularly when the surrounding trees change color in autumn.
Okususo offers something different throughout the year. Spring brings the spectacular blooming of mizubasho as the snow melts. In summer, the cool shade of the beech forest provides a refreshing escape from the heat. Autumn transforms the mountains into a vivid display of red and yellow foliage, while the landscape becomes especially quiet and secluded during the colder months.
Okususo Nature Garden and Okususo Gorge bring together pristine forests, expansive wetlands, spectacular seasonal scenery, and fascinating geological formations in one remote mountain setting.
The vast colonies of mizubasho, unusual rock formations, folded strata, and peaceful walking trails offer a chance to experience a side of Nagano far removed from the city’s historic temples and busy tourist areas. For travelers seeking mountain landscapes, wildflowers, hiking, photography, and the quiet beauty of Japan’s lesser-known natural destinations, Okususo is a memorable place to explore.