Right Onsen › Tokyo › Niijima
Sankai-no-Yu
3.9★ · 12 Google ratings · Niijima, Tokyo · 山海の湯
✓ Day visitors✓ Outdoor bath✓ Kakenagashi
Before you go
Can you bathe here?
Day visitors
✓ YesReported by two visitors
Hours
00:00–24:00From the facility's listing
Tattoos
? Call aheadNo policy stated in the 12 recent reviews we read
Price
Free adultReported by two visitors
How we know this
- Day visitors: Visitors in 2025 reported the spring is open 24 hours with no admission fee, though a swimsuit is recommended and tide timing limits when it can actually be used. · 2 visitors, May 2025 – Sep 2025
- Price: The bath is free of charge, but access depends entirely on tide levels rather than fixed hours. · 2 visitors, May 2025 – Sep 2025
The bath
What you’ll find
Sankai-no-Yu is a free, unmanned natural hot-spring pool on a rocky ocean shoreline near Ashitsuki Onsen, bathable only around low tide, with slippery footing that can be dangerous, especially in rain or at night.
Bath setup
Outdoor bath
✓ YesConfirmed by recent visitor reports
Outdoor baths
1Reported by two visitors
View
OceanReported by two visitors
Spring water
Source temperature
50°CReported by one visitor
Free-flowing (kakenagashi)
✓ FullFresh spring water flows continuously through the bath
How we know this
- Outdoor bath: The bath is a set of natural rock hollows on the shoreline that fill with hot spring water, visible mainly at low tide between 2022 and 2025. · 3 visitors, Sep 2024 – Sep 2025
- Outdoor baths: There is one natural bathing area made up of a few connected rock hollows rather than separate built baths. · 2 visitors, May 2025 – Sep 2025
- View: The bath sits directly on the ocean shoreline, reachable by walking along the coast from Ashitsuki Onsen. · 2 visitors, Jan 2023 – May 2025
- Source temperature: A 2025 visitor measured the middle rock hollow at over 50°C near the spring source. · 1 visitor, May 2025
- Free-flowing (kakenagashi): The spring water self-fountains directly from the seabed rocks with no recirculation or added water, as described in 2022 and 2025 reviews. · 2 visitors, Jan 2022 – May 2025
Guide
Good to know
Outdoor bath
The bath is a set of natural rock hollows on the shoreline that fill with hot spring water, visible mainly at low tide between 2022 and 2025.
Confirmed by recent visitor reportsSource temperature
A 2025 visitor measured the middle rock hollow at over 50°C near the spring source.
Reported by one visitorTiming
When to go
Quietest Tuesday around 22:00. Busiest Friday around 10:00.
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Quiet Busy
Based on Google visit patterns, not a forecast.
Weekly hours
| Day | Hours |
|---|---|
| Monday | 00:00–24:00 |
| Tuesday | 00:00–24:00 |
| Wednesday | 00:00–24:00 |
| Thursday | 00:00–24:00 |
| Friday | 00:00–24:00 |
| Saturday | 00:00–24:00 |
| Sunday | 00:00–24:00 |
Getting there
How to get there
Nearest station
Minami-machida Grandberry Park134.5 km in a straight line; bus or taxi from the station
Address
1006 Shikinejima, Niijima, Tokyo 100-0511From the facility's listing
Show a driver
山海の湯The name in Japanese, for a taxi or at the counter
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Questions
Common questions
Can I visit Sankai-no-Yu without staying overnight?
Visitors in 2025 reported the spring is open 24 hours with no admission fee, though a swimsuit is recommended and tide timing limits when it can actually be used.
How much does Sankai-no-Yu cost?
The bath is free of charge, but access depends entirely on tide levels rather than fixed hours.
Is the water free-flowing spring water?
The spring water self-fountains directly from the seabed rocks with no recirculation or added water, as described in 2022 and 2025 reviews.
