A Spectacular Lake at 1,731 Meters Above Sea Level
Lake Suganuma lies in the eastern part of Katashina Village, at the northern foot of Mount Nikko-Shirane. The lake has a surface elevation of approximately 1,731 meters, an area of about 0.77 square kilometers, a shoreline of approximately 6.5 kilometers, and a maximum depth of about 75 meters.
Its shoreline is deeply indented, and the lake is divided into three basins from east to west: Shimizu-numa, Benten-numa, and Kitamata-numa. These three basins are collectively known as Lake Suganuma.
The lake’s water flows out through Haccho Falls (Hacho Falls) on the western side before eventually reaching Lake Marunuma downstream. The tranquil water surrounded by pristine forests creates an atmosphere reminiscent of a secluded lake in Northern Europe.
A Beautiful Landscape Created by Volcanic Activity
A Lake Formed by a Natural Lava Dam
Lake Suganuma is a dammed lake formed when lava produced by volcanic activity at Mount Nikko-Shirane blocked a river. This geological formation is not only visually impressive but also significant from a scientific and geographical perspective.
Hydroelectric power facilities were developed in the 1930s, and water from Lake Suganuma began to be conveyed downstream toward Lake Marunuma. This is believed to have contributed to the separation of what was originally a single body of water into three distinct lake basins.
Even today, the lake’s water level fluctuates as part of its use for hydroelectric power generation, influencing the environment along the shoreline.
Exceptional Clarity of an Oligotrophic Lake
Lake Suganuma is classified as an oligotrophic lake, meaning that its water contains relatively few nutrients and remains remarkably clear. Its recorded water transparency is approximately 13 meters, considered the highest among lakes in Honshu. Historical records indicate that visibility once reached as much as 19 meters.
Fed partly by snowmelt, the lake remains cool even during summer. Depending on the season, weather, sunlight, and time of day, the water can appear deep blue, vivid blue-green, or emerald green. The changing colors of the lake are one of its most captivating features.
Enjoy Nature Through Outdoor Activities
Explore the Lake by SUP or Canoe
In recent years, SUP (stand-up paddleboarding) has become a popular way to experience Lake Suganuma. The calm surface of the lake makes it possible to enjoy a leisurely paddle while taking in the surrounding mountain and forest scenery.
SUP is also an enjoyable form of exercise that engages the core muscles, making it popular not only with visitors but also with people looking for off-season or cross-training activities.
Other activities include canoeing, birdwatching, and stargazing. After sunset, the high elevation and clean mountain air create ideal conditions for enjoying a spectacular night sky filled with stars.
Fishing and Trout Farming
Rainbow trout and brown trout are stocked in the lake, making Lake Suganuma a popular destination for both lure fishing and fly fishing. Spending a quiet afternoon casting a line amid the surrounding wilderness offers a peaceful escape from the bustle of city life.
Trout farming is also carried out in the surrounding area, making trout an important part of the region’s local character.
Experience the Great Outdoors at Lake Suganuma Campground
Lake Suganuma Campground is a large campground located beside the lake. In addition to fishing and canoeing, visitors can enjoy facilities and activities such as a dog run and forest walks, making the area suitable for families as well as experienced outdoor enthusiasts.
Camping beside the crystal-clear lake and surrounded by pristine forest offers a particularly memorable experience. The scenery changes throughout the day, from a lake covered in morning mist to skies glowing at sunset and countless stars appearing overhead at night.
Exploring the Lake Marunuma and Lake Suganuma Area
From Numata, follow National Route 120, also known as the Konsei Road, toward Konsei Pass. Lake Suganuma and Lake Marunuma are located close to one another, approximately one kilometer before the Konsei Pass Tunnel.
Lake Suganuma lies upstream, while Lake Marunuma is downstream. Both are dammed lakes formed by lava from Mount Nikko-Shirane.
In 1931, a dam was constructed between Lake Marunuma and Lake Oshiri-numa, significantly raising the water level of Lake Marunuma. This also affected Lake Suganuma and helped shape the landscape seen today.
The drive between the two lakes is a popular scenic route, offering beautiful views that change dramatically with the seasons. Fresh greenery in spring and summer, brilliant autumn foliage, and snowy winter landscapes each create a different atmosphere.
Access
By Public Transportation
From JR Numata Station, take a local bus toward Marunuma Kogen Ski Resort. The journey takes approximately 105 minutes, followed by a walk to the lake.
By Car
From the Numata Interchange on the Kan-Etsu Expressway, take National Route 120 (Konsei Road). The journey takes approximately 90 minutes. Free parking is available.
However, the road and surrounding facilities are generally closed during the winter season, from around late December to late April. Visitors should check the latest road and access conditions before traveling.
Enter a World of Silence and Crystal-Clear Water
Lake Suganuma is a special destination where volcanic landscapes, exceptionally clear water, and pristine forests come together in a peaceful mountain setting. In summer, visitors can enjoy the cool mountain air; in autumn, brilliant foliage is reflected on the lake; and in spring, lingering snow contrasts beautifully with fresh green vegetation.
Standing beside the clear blue water and looking across the quiet lake, it is easy to forget the noise and routines of everyday life. For travelers seeking a deeper connection with nature, Lake Suganuma offers an unforgettable experience and a destination worth returning to in every season.