Japan's highest paved national road, 2,172m up on the Gunma–Nagano border, where dawn temperature inversions bury the valley in a sea of clouds below your feet.
At 2,172 metres above sea level, Shibu Pass (渋峠, Shibu-tōge) carries National Route 292 over the shoulder between Mt. Yokote and Mt. Kusatsu-Shirane — the highest point reached by any national highway in Japan. It sits directly on the border between Nakanojo, Gunma and Yamanouchi, Nagano; the Shibutoge Hotel at the pass is famously built two-thirds in one prefecture and one-third in the other, with a line marked across the floor.
Why It’s Interesting
Because the road climbs so high above the surrounding valleys, cold mountain air often traps a layer of cloud beneath the ridge on calm mornings — the phenomenon known in Japan as unkai (雲海, “sea of clouds”). Stand at the pass at sunrise and the valley you drove up through can have vanished entirely under a flat white expanse, with only the highest peaks — sometimes as far as Mt. Fuji, Lake Suwa, and the Northern Alps — poking through.
Best Time to Visit
The pass is snowed shut roughly mid-November through late April. Within the open season, dawn sea-of-clouds views are reported most consistently from September into early November, as the season’s first strong temperature inversions set in before the road closes for winter — good news for anyone planning a fall trip like this one.
Getting There
Route 292 is a mountain road with no rail or bus service; you’ll need a car. It’s part of the wider Shiga Kōgen / Shiga-Kusatsu-kōgen route linking Gunma and Nagano, and it’s roughly a 40-minute drive down the mountain to Jigokudani Monkey Park, making the two an easy pairing on the same trip. Check road-closure status before heading up, since conditions can change quickly at this altitude even outside the official winter closure.
🐿️ Cinnamon was here
Field report
A traveler wrote in planning a September drive up from Kawasaki, chasing something called unkai — clouds seen from above — and I could not let that go unverified.
I rode the last stretch in a delivery van's door pocket and got out at 2,172m with my fur standing straight up from the cold. Route 292 was empty and silent, and below the ridge the whole valley had filled overnight with cloud, flat and white as a lake, while the peak stood in clear morning sun. I sat on the guardrail eating a pinecone and felt, briefly, like the tallest creature in Japan.
Other visitors say the same thing every time: come before sunrise, because the cloud lake can be gone within the hour, and dress like it's winter even in September — the valley floor and the pass can be 15 degrees apart. The road shuts for snow by mid-November, so a September visit, like the traveler's, is close to ideal timing. Jigokudani's monkeys are about forty minutes down the mountain if you want warm water after all that cold air.
— Cinnamon 🐿️
📸 Cinnamon's camera roll
Snapshots from our very good boy on the road.
Where it is
You might also like
Jigokudani Snow Monkey Park
Yokoteyama Skylator
Shibu Onsen
Onioshidashi Park
Nearby discoveries
Chatsubomi Moss Park
Takasaki Byakue Daikannon
Nagatoro River Rafting
Tateyama Snow Wall (Yuki-no-Otani)
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