RENT & RIDE JAPANJoshu, Shimagawa Dam & Sawatari Onsen
Shima Blue & Sawatari Onsen Day Trip
A one-day autumn ride from Hachioji up the Kanetsu Expressway to the cobalt-blue Oku-Shima Lake (Shimagawa Dam) and the historic Sawatari Onsen, wrapped in early foliage along the Agatsuma River.
- DISTANCE
- 340 km
- DURATION
- 11 h
- LEVEL
- Intermediate
Starting from TASHILOG GARAGE in Hachioji, this one-day tour heads north on the Kanetsu Expressway into Gunma, then follows the Agatsuma River west into the mountains of the Joshin'etsu-kogen National Park. Enjoy quiet highland villages and early autumn colors before soaking in a classic hot spring.
Highlights
- Oku-Shima Lake (Shimagawa Dam): A castle-like stone-faced dam and a reservoir whose water shifts through shades of cobalt known as "Shima Blue." The loop road around the lake is a treat for winding-road fans.
- Sawatari Onsen: A serene, traditional cure-bath town long known as the "finishing bath" after Kusatsu.
- Agatsuma Gorge & riverside autumn scenery: Colorful ravines and peaceful rural landscapes.
Riding notes
The lake loop road closes in winter, so autumn is the ideal window. It's a full day even as a round trip, so start early.
- 1START
Tashilog Garage
Start point. Leave Hachioji early and head to Gunma via the Ken-O and Kanetsu Expressways.
TIPSFuel up and check tire pressure before departure. An early start makes the long day more comfortable.
- 2SPOT~15 min
Shibukawa-Ikaho Interchange
The exit off the Kanetsu Expressway. From here head west toward Agatsuma along Route 353.
TIPSTop up fuel and take a restroom break near the IC before entering the mountains.
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Photo: Yasu (talk) / Wikimedia Commons / CC BY-SA 3.0 - 3VIEW~45 min
Oku-Shima Lake (Shimagawa Dam)
The cobalt-blue reservoir of the Shimagawa Dam. Ride the loop road around the lake and take in the views.
HISTORYCompleted in 1999, the Shimagawa Dam is a gravity concrete dam whose 89.5 m height makes it the tallest dam operated by Gunma Prefecture. Its stone-faced body evokes a Western castle, and it is designated an 'open to the community' dam.
TIPSThe water is famed as 'Shima Blue,' shifting color with light and time of day. The loop road runs about 4 km and closes in winter, so visit by autumn. Dam cards are available on site.
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Photo: 河川一等兵 / Wikimedia Commons / Public domain - 4VIEW~20 min
Shima Lake (Nakanojo Dam)
Another reservoir at the gateway to Shima Onsen, a popular Shima Blue spot also known for canoeing and SUP.
TIPSDownstream of Oku-Shima Lake along the same road. The clear blue surface contrasts beautifully with the surrounding autumn foliage.
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Photo: pokopokopokopoko / Wikimedia Commons / CC BY-SA 3.0 - 5FOOD~60 min
Cafe & Soba Nagai
A long-established soba restaurant in Shima Onsen, founded in 1924. Enjoy lunch with hand-made soba.
TIPSFounded in 1924, they hand-make only the day's portion of soba each day using local buckwheat flour and Shima water. The elevated tatami room overlooks the Shima River gorge. Renovated in 2021; please confirm opening days and hours in advance.
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Image - 6ONSEN~60 min
Sawatari Onsen Public Bath
A day soak at Sawatari Onsen's public bathhouse, fed directly from the source, to ease the day's fatigue.
HISTORYSawatari Onsen is a quiet hot-spring town on the upper Kami-Sawatari River, long cherished as the 'finishing bath' after a Kusatsu cure. Its waters are said to leave skin smooth as a jewel.
TIPSOpen in Google MapsSeparate men's and women's baths each have a hot and a warm tub to suit your condition. Day-use only, with parking. Hours and fees may change, so please confirm in advance.
- 7SPOT~20 min
Michi-no-Eki Nakanojo
A rest stop on the way back, offering local Nakanojo produce and souvenirs.
TIPSOn the return, descend east along the Agatsuma River from Nakanojo to Shibukawa-Ikaho IC. A good spot for a short break and souvenirs.
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Photo: Filler / Wikimedia Commons / CC BY-SA 3.0 - 8GOAL
Tashilog Garage
Return. Head back to Hachioji via the Kanetsu and Ken-O Expressways to end the day.
TIPSThe Kanetsu Expressway is prone to evening congestion, so plan the return with some buffer time.
