Oe Marshland is a vast wetland located at the upper reaches of Lake Ozenuma and is one of the most scenic areas in Oze. The wetland is second in size only to Ozegahara Marshland and is also known as Oegawa Marshland, after the Oe River that flows through its center.
Located at an elevation of approximately 1,665 meters, Oe Marshland is higher than Ozegahara. Its elevation gives the area distinctive climatic and ecological characteristics, supporting a unique variety of wetland and alpine plants.
The area was once part of Lake Ozenuma, but gradually developed into a wetland over a very long period of time. The landscape still provides an opportunity to observe the continuing natural transition from lake to wetland.
The expansive marshland, surrounded by mountains, creates a remarkable landscape that leaves a lasting impression on visitors.
Oe Marshland is sometimes described as a “wetland of flowers” because of the wide variety of alpine plants that bloom throughout the seasons. Its most famous summer attraction is the magnificent colony of Nikko kisuge daylilies.
From around late July, large areas of the marshland can be covered in vivid yellow flowers, creating the appearance of an enormous yellow carpet. The density of the flowers is considered among the most impressive in Oze, and in particularly good years, the blooms can stretch across the entire field of view.
Because Oe Marshland is located at a higher elevation, its flowering season generally arrives about one to two weeks later than in Ozegahara. This difference in timing allows visitors to enjoy the flower season across different parts of Oze for a longer period.
In addition to Nikko kisuge, seasonal plants such as Asian skunk cabbage and cotton grass add color to the wetlands throughout the year, giving the landscape a different appearance with each visit.
A wooden boardwalk runs through the center of Oe Marshland, following part of the historic Aizu-Numata Kaido, an old route that once connected Aizu with the Joshu region, now part of Gunma Prefecture.
The route was historically important as a trade and transportation route. Today, it has become a popular walking trail where hikers can experience both the history and natural beauty of Oze.
As you walk through the open wetland, you can enjoy impressive views of Mount Hiuchigatake in the distance and the calm waters of Lake Ozenuma, whose surface can reflect the surrounding sky and mountains like a mirror.
The boardwalks also help protect the fragile wetland vegetation by allowing visitors to enjoy the landscape while minimizing their impact on the natural environment.
One of the most common ways to reach Oe Marshland is to travel from the Fukushima side to Numayama Pass by bus from Mikage, then continue on foot.
After passing through a forest of Maries’ fir trees and crossing gently undulating terrain, the forest suddenly opens up to reveal the vast panorama of Oe Marshland. The dramatic change from dense forest to open wetland is one of the highlights of the approach.
From the Gunma side, another route begins at Oshimizu and crosses Sanpei Pass. Although this route is longer, it is suitable for hikers looking for a more substantial trekking experience.
There are also trails leading toward Kobuchizawa Tashiro and longer traverses continuing toward the Okukinu Onsen area. These options provide a variety of hiking experiences depending on the visitor’s fitness level, experience, and itinerary.
The northern shore route of Lake Ozenuma, which connects Oe Marshland with Numajiri, is a varied trail where wetlands and forests alternate along the route.
Walking along the foothills of Mount Hiuchigatake, hikers can enjoy views of small wetlands scattered around the lake’s bays as well as peaceful waterside scenery.
The shoreline is home to aquatic plants such as giant bulrush, while waterfowl including ducks and herons can sometimes be observed. This makes the route particularly appealing for nature observation.
Small animals such as squirrels and stoats may also be encountered in the forest, making every section of the trail an opportunity for a new discovery.
In recent years, increasing populations of Japanese deer have affected vegetation in parts of Oe Marshland. The Ministry of the Environment and local authorities have been implementing measures such as installing deer-exclusion fences to protect vulnerable plant communities.
These conservation efforts help preserve both the beautiful scenery and the delicate ecosystem of the wetlands.
Oze is often described as a place closely associated with the origins of Japan’s nature conservation movement. Its natural environment has been maintained through the efforts of many people over the years.
Visitors are therefore asked to follow conservation rules, including staying on the designated boardwalks and never picking plants. Even small actions by individual visitors can help protect this fragile landscape.
Oze is a vast national park extending across Gunma, Fukushima, Niigata, and Tochigi prefectures, and contains one of Japan’s largest high-altitude wetland areas.
Ozegahara lies to the west and Lake Ozenuma to the east. The formation of the area’s distinctive landscape can be traced back approximately 2 million years to volcanic activity.
In spring, Asian skunk cabbage blooms across the wetlands. In summer, Nikko kisuge daylilies create fields of yellow, while autumn brings golden grasses and colorful foliage to the surrounding mountains.
During winter, the area is covered in deep snow and the hiking season comes to an end. Although visitors cannot normally explore the wetlands during this period, the snow plays an important role in protecting the natural environment and sustaining the ecosystem until spring.
Weather conditions in the mountains can change quickly, and temperatures can vary considerably between morning and evening. Visitors should prepare appropriately for these conditions.
Waterproof hiking shoes, rain gear, and warm clothing are recommended for a comfortable and safe trip. The wooden boardwalks can also become slippery after rain or when covered with frost, so hikers should take particular care with their footing.
Spending time in the open landscape of Oe Marshland offers an experience far removed from everyday life. Surrounded by expansive wetlands, alpine flowers, mountains, and clear mountain air, visitors can enjoy a peaceful journey through one of Oze’s most beautiful natural landscapes.