Bungo-ono, Oita / 稲積水中鍾乳洞
Inazumi Underwater Cave
On the upper reaches of the clear Hakusan River, one of Japan's 100 best waters, the largest underwater limestone cave in Japan, where stalactites can be seen under water - rare even worldwide. It formed over 200 million years ago and is said to have been submerged by the great Aso eruption 83,000 years ago. There are also a museum and a "Showa shopping street", with a campground next door; fireflies can be seen on the Hakusan River from late May to mid June.
Last official check
26 Sept 2026
Traveler reports
0
Reports open in Phase 2
Next scheduled check
25 Dec 2026
Decide before you go
A short summary made from the official facts below. Check the rows for details.
- Getting there
- Train / Bus / Car
- Closing days
- Has closing days (see below)
Before you go
Only facts we confirmed on official sources are shown. Anything else is marked “Not checked yet”.
- Opening hours
9:00-17:00 (longer in summer).
Checked 26 Sept 2026 on the official site- Closed
Open every day.
Checked 26 Sept 2026 on the official site- Admission
Not checked yet — we have not confirmed this on an official source yet. Check with the spot before you go.
- Getting there
20 minutes by car from Bungo-Mie-machi Station (JR Hohi Line); 1 minute on foot from the Inazumi Suichu Shonyudo bus stop.
Checked 26 Sept 2026 on the official site- Parking
Not checked yet — we have not confirmed this on an official source yet. Check with the spot before you go.
- Payment
Not checked yet — we have not confirmed this on an official source yet. Check with the spot before you go.
- Accessibility
Not checked yet — we have not confirmed this on an official source yet. Check with the spot before you go.
Found wrong or outdated information? Let us know
Address: Bungo-ono, Oita (Japanese address: 大分県豊後大野市三重町中津留300)
Official site: https://www.visit-oita.jp/spots/detail/4495
Location
Smaller pins are other spots nearby.
Nearby spots
- No photo yetHarajiri FallsOita11 km away (straight line)
- No photo yetOka Castle RuinsOita15 km away (straight line)
Distances are straight-line distances, not travel distances.
Crowds
- Crowd level
Not checked yet — no official source yet, and not enough traveler reports.
- Best time to visit
Not checked yet — no official source yet, and not enough traveler reports.
- Peak time
Not checked yet — no official source yet, and not enough traveler reports.
- Busiest days
Not checked yet — no official source yet, and not enough traveler reports.
- Busiest season
Fireflies on the nearby Hakusan River from late May to mid June.
Checked 26 Sept 2026 on the official site- Latest traveler report
- None yet
Traveler crowd data by time of day appears after 5 traveler reports (0 so far).
You can check typical busy hours in Google Maps ("Popular times" on the place's page). Open this spot in Google Maps
Verification log
- 26 Sept 2026First check · Tourism board · https://www.visit-oita.jp/spots/detail/4495Hours, closing days, access, description, address and coordinates read from a tourism organization's site.