Okushima Lake is unbelievably dreamy. No wonder everyone calls it the "Shima Blue." It looks even more stunning in person.

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Okushima Lake
A mystical lake famed for its striking blue hue, known as “Shima Blue.”
A lake formed by the Shima River Dam, Okushima Lake lies deep in the mountains, about 30 minutes by car from JR Nakanojo Station, following National Route 353 north to its end.
The water is renowned for its mysterious blue tones-ranging from cobalt and indigo to turquoise-which shift with the season and conditions. This ever-changing palette has earned the name “Shima Blue,” drawing photographers and visitors from afar.
A 4-kilometer one-way loop road circles the lake and is drivable by car. Around the shore, spots like Seseragi Park and observation decks invite leisurely stops, while canoeing and SUP are also popular on the water.
The blue is at its most vivid from April to May, when snowmelt flows in. On clear mornings, sunlight sparkles across the surface-an especially photogenic time.
Beyond the green season, autumn foliage (mid-Oct to early Nov) and winter snowscapes offer striking contrasts, making the lake captivating year-round.
Highlights
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A dam lake created by the Shima River Dam.
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Famous for its mystical blue water known as “Shima Blue.”
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A 4-kilometer one-way loop road allows visitors to drive around the lake.
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Water activities can be enjoyed during the green season.
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In autumn, fall foliage and in winter, snowy landscapes create beautiful contrasts with the blue water, making it appealing in every season.
Photos
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Turquoise blue phase: A breathtaking sight you rarely see in an ordinary lake.
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Indigo blue phase: Clear water reflects blue light-proof of the lake’s exceptional clarity.
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Enjoy water activities such as canoe tours.
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Surrounding autumn foliage pairs beautifully with the lake.
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In winter, the striking contrast between snowy scenery and deep blue water makes Okushima Lake truly unforgettable.
Official FAQs
Frequently Asked Questions have been vetted and answered directly by each listing.
Q
Do you have signs or pamphlets in foreign languages? (If you do, which languages are available?)
Sorry, we don’t.
Q
Is free Wi-Fi available in the area?
Yes, it is.
Q
Are coin lockers available?
Not available.
Q
Are there restrooms available?
Yes, there are.
Q
Are there any smoking areas?
Not available.
Reviews
Some reviews are AI-translated.
Details
- Name in Japanese
- 奥四万湖
- Postal Code
- 377-0601
- Address
- Shima, Nakanojo-machi, Agatsumagun, Gunma
- Telephone
- 0279-64-2321(Shiman Onsen Association)
- Access
- About 28 minutes by car from JR Nakanojo Station.
- Official Website
- Official Website (Japanese)