What many overlook is that this part of Gunma isn't just about hot springs; it's also about quiet water, forest roads, and a very photogenic shade of blue. That combination feels like classic Japan, doesn't it?
Gunma's blue lakes near Shima Onsen
Gunma's blue lakes don't always show up on the first page of travel guides, and that's exactly why they work so well as a summer trip. In the Nakanojo area, close to Shima Onsen, you can find two small lakes that look almost unreal when the weather's clear. The water has that crisp, bright blue tone that makes you stop, look twice, and then reach for your camera.
For Japan fans, this is a nice reminder that not every memorable place needs a big shrine, a famous castle, or a crowded train station. Sometimes it's just a still body of water, a mountain road, and the smell of cedar in the air. My tip: pair the visit with a night at a ryokan, then let the day end in an onsen bath. Sounds good, right?
Two quiet waters in the Nakanojo area
The two lakes are part of what makes this corner of Gunma worth the detour. They're not massive sightseeing spots, which is part of the appeal, and they're surrounded by greenery that changes with the season. In summer, the trees frame the water like a natural border, and the blue stands out even more.
A great example: if you've ever studied the word 水 (mizu) for water, this is one of those places where the visual memory sticks. The colour isn't just pretty, it's clear enough that you can often see the bottom near the shore, depending on light and angle. No exaggeration: the scene feels calm in a way that busy tourist lakes often don't.
Why the blue looks so striking
What many overlook is that the colour of mountain water changes with depth, minerals, sunlight, and the surrounding forest. On a bright day, the lake can shift between turquoise and a deeper sapphire tone, and that makes it a gift for photographers. If you're learning Japanese, this is a good chance to notice words like 青い (aoi) for blue, 湖 (Mizuumi) for lake, and 綺麗 (kirei) for beautiful.
That brings us to the best part: the atmosphere. You don't need a packed itinerary here. You can simply stand by the bank, listen to insects in summer, and enjoy the stillness. Simply lovely.
Shima Onsen adds the perfect onsen stay
Shima Onsen is the natural base for this kind of trip. The area sits in Nakanojo, and it has long been known as a hot spring town with a slower pace than bigger resort destinations. If you've heard the old saying that Shima's water is good for the skin, that's part of the town's appeal, and it's one reason people have been coming here for generations.
Here's the catch: the lakes are lovely on their own, but the experience becomes much better when you combine them with a proper onsen stop. After a walk by the water, a soak in hot spring water feels almost perfectly timed. A ryokan dinner, a quiet night, and then the next morning's mist over the hills, that's the kind of travel rhythm I always enjoy. Insider tip: stay overnight if you can, because day trips always feel rushed here.
How to plan the visit
Fun fact: Nakanojo is also known for its flower and art events, so the broader area has more to offer than just hot springs and lakes. But for a summer route, I'd keep it simple. Start with the water, move on to Shima Onsen, and leave room for an unplanned stop at a roadside viewpoint. Japan rewards that kind of flexibility.
Know that feeling when a place doesn't need much explanation? This is one of those. The landscape does the work, and you just get to enjoy it. My verdict: Gunma's blue lakes are exactly the sort of under-the-radar destination that Japan travellers should keep on their map.
Japanese travel vocabulary for lake days
For learners, this trip is a nice excuse to pick up a few useful words. Mizuumi means lake, onsen means hot spring, and 山 (yama) means mountain, which you will probably hear or see a lot in this area. If you like making study notes from real places, Gunma is great for that because the place names and scenery line up so neatly.
What most people don't know is that learning in context helps the words stick faster than memorising a list. When you connect a term like ryokan with an actual stay, or aoi with the blue of the water, it becomes easier to recall later. And if you visit during summer, you may also hear 夏 (natsu) for season talk everywhere, from station signs to local souvenirs. Personally, I think that kind of learning is much more memorable than textbook examples.
So if you want a summer route that mixes nature, onsen culture, and a little language learning, this corner of Gunma is a strong pick. It won't shout for attention, and that's exactly why it feels special. more Japan news on jpnerd.com
Frequently Asked Questions
Where are these blue lakes located?
They are in the Nakanojo area of Gunma, near Shima Onsen.
Can I visit them as a day trip?
Yes, but staying overnight makes the onsen part much easier and more relaxing.
What is the best season to go?
Summer works especially well because the blue water stands out against the green mountains.
