Lake Akaya is a beautiful reservoir in Minakami Town, Gunma Prefecture, created through the construction of the Aim ata Dam. Surrounded by the magnificent natural landscapes of the Tanigawa Mountain Range and Mikuni Mountains, the lake changes its appearance with every season and attracts visitors throughout the year.
Sarugakyo Onsen spreads along the lakeshore, creating a scenic setting where mountain nature and traditional hot springs come together. The combination of the lake, mountains, and hot spring town makes Lake Akaya one of the notable sightseeing destinations in Gunma.
The greatest attraction of Lake Akaya is its rich natural scenery. In spring, cherry blossoms bloom along the lakeshore, and their flowers are reflected on the calm surface of the lake, creating a peaceful atmosphere.
From early summer through summer, the surrounding mountains become covered in increasingly deep green foliage. A refreshing breeze often travels across the lake, making this an ideal season for lakeside walks and hiking.
In autumn, the surrounding mountains are transformed by brilliant red and yellow autumn foliage. The colorful trees reflected on the surface of the lake create an especially spectacular landscape.
Winter brings snow-covered mountains and a quiet lake, creating an almost dreamlike atmosphere. The crisp winter air and peaceful scenery offer visitors a different way to appreciate the beauty of Lake Akaya.
Every May, the lake also becomes the setting for a seasonal tradition featuring colorful koinobori carp streamers. The carp-shaped streamers appear to swim through the sky above the lake, creating a striking scene against the blue sky and surrounding mountains.
The well-maintained Lake Akaya Lakeside Walking Trail follows the shoreline and allows visitors to enjoy a leisurely walk around approximately half of the lake.
The route connecting the Sarugakyo Sekisho Museum and Aim ata Dam is relatively easy to walk, offering views of the lake and surrounding mountains along the way.
Several attractions can be found along the route, including a boat dock, parks, a dam information center, and observation points. Visitors can take their time exploring the area and enjoying the scenery.
A popular option is a circular walking route starting from the day-use hot spring facility Mantenboshi no Yu. Combining a lakeside stroll with a relaxing hot spring bath is one of the enjoyable ways to experience the area.
Mantenboshi no Yu
Sarugakyo Sekisho Museum
Lake Akaya Lakeside Walking Trail
Aimata Dam
Large Ginkgo Tree at Kaienji Temple
Komagata Gorge on the Akaya River
Lake Akaya lies within the natural environment of the Tanigawa and Mikuni mountain ranges, which are part of a UNESCO-designated biosphere reserve. The clear mountain air and spectacular scenery are an essential part of the lake’s appeal.
Aimata Dam is a 67-meter-high concrete gravity dam built on the Akaya River, part of the Tone River system. It is a multipurpose dam managed by the Kanto Regional Development Bureau of the Ministry of Land, Infrastructure, Transport and Tourism and plays an important role in supporting the water resources of the Tokyo metropolitan area.
The dam was planned as part of comprehensive flood-control measures for the Tone River system following the devastating damage caused by Typhoon Kathleen after World War II.
The main structure was completed in 1956, followed by subsequent repair work, and the dam was officially completed in 1959. Today, it continues to serve several important functions, including flood control, securing water supplies, and hydroelectric power generation.
In recent years, dam improvement projects have been undertaken to strengthen its flood-control capabilities. The dam is located in a steep V-shaped valley, where visitors can see its tall and imposing structure up close.
The view from the top of the dam is particularly impressive, offering a panoramic perspective over Lake Akaya and the surrounding mountains.
Sarugakyo Onsen, a well-known hot spring resort, extends along the shores of Lake Akaya. The original hot spring settlement was located along the Akaya River but was submerged following the construction of the dam.
The hot spring sources themselves were preserved, however, and a new hot spring town was rebuilt beside the lake.
Today, numerous hotels and traditional inns stand in locations overlooking Lake Akaya, and Sarugakyo has developed into one of Gunma’s notable hot spring resorts.
National Route 17, the former Mikuni Kaidō highway, runs nearby. This route historically served as an important transportation link between Echigo, corresponding broadly to present-day Niigata, and Kōzuke, the historical name for the region that includes present-day Gunma.
During the Sengoku period, the warlord Uesugi Kenshin is also said to have crossed the Mikuni Pass on military campaigns into the Kantō region.
The hot spring water at Sarugakyo Onsen is classified as a sodium-calcium sulfate-chloride spring, with source temperatures ranging from approximately 42°C to 58°C.
The water is known for its warming properties and has traditionally been used for bathing associated with conditions such as neuralgia, muscle pain, and sensitivity to cold.
Approximately 16 hotels and traditional inns stand around Lake Akaya, while there are around 40 accommodation facilities in the wider area, including smaller hot spring guesthouses.
The dedicated day-use bathing facility Mantenboshi no Yu allows visitors to enjoy the hot springs without staying overnight. Many of the local accommodations also offer day-use bathing, making it possible to stop for a bath while sightseeing around the lake.
In 2005, Lake Akaya was selected as one of the 100 Selected Dam Lakes of Japan following a recommendation from Minakami Town. The selection recognized qualities including the lake’s scenic beauty and its contribution to regional development.
Across the lake, visitors can see the streets of Sarugakyo Onsen, while Mount Mikuni can be seen in the distance.
The combination of lake, mountains, and hot spring town creates a distinctive landscape that leaves a lasting impression on visitors.
Lake Akaya is much more than a reservoir. While Aimata Dam plays an important role in flood control and water resource management, the lake has also become an attractive destination for sightseeing.
Visitors can enjoy a variety of experiences, including lakeside walks, dam sightseeing, hot spring bathing, and exploring local history.
With its magnificent natural surroundings and the long history of human activity around it, Lake Akaya and Sarugakyo Onsen offer a peaceful destination where visitors can slow down, enjoy the scenery, and experience the harmony between nature and local life.