These are two separate lava-tube caves on the western edge of Aokigahara forest, formed by a Mount Fuji eruption roughly a thousand years ago, and they're commonly visited together. Narusawa Ice Cave keeps a near-freezing temperature year-round and has ice formations on its walls and floor even in summer, while the nearby Fugaku Wind Cave is cooler and drier and was historically used to store silkworm eggs and seeds because of its stable low temperature. Both are walked as short underground loops with low ceilings in places.
Narusawa Ice Cave and the nearby Fugaku Wind Cave are two lava-tube caves formed by Mount Fuji's 864 CE Jogan eruption, both sitting within the Aokigahara forest and maintaining a naturally cold, humid environment year-round because their below-ground chambers trap cold air. Narusawa Ice Cave is smaller and steeper, with a narrow single-file walking route down through icicles and ice pillars that build up through the winter and, remarkably, persist through summer due to the cave's insulated microclimate; visitors descend a series of ladders and low passages, so the route requires reasonable mobility and is not suited to anyone uncomfortable in tight spaces. The larger Fugaku Wind Cave, a short drive or walk away, has a more level walking route through a longer lava-tube system historically used to store silkworm eggs and seeds at a stable cold temperature before refrigeration, with some of that storage history explained through on-site panels and preserved storage racks. Both caves maintain temperatures near 0°C (32°F) year-round regardless of the season outside, making them a popular midsummer stop for visitors escaping the heat, though the cold, damp conditions mean a jacket is worth carrying even in August. A combined ticket for both caves offers a modest discount over separate admission, and the two sites sit close enough together to visit in the same outing along the northern edge of Aokigahara.
| Admission | Adult ¥400 ($2.50) Narusawa Ice Cave; ¥400 ($2.50) Fugaku Wind Cave; combined ticket approx ¥720 ($4.50) · Child Reduced child rate at each cave |
|---|---|
| Hours | 9:00am–5:00pm (varies seasonally, extended in summer, shortened in winter) |
| Typical visit | 45–90 minutes for both caves |
| Best time | Summer, when the caves offer natural cool relief and ice formations are at their thickest from winter accumulation |
| Getting there | Bus from Kawaguchiko Station toward Narusawa, or a short drive from Lake Saiko |
| Address | 8533 Narusawa, Narusawa, Minamitsuru District, Yamanashi 401-0320 |
Location
8533 Narusawa, Narusawa, Minamitsuru District, Yamanashi 401-0320
35.4706, 138.6231 View on map
Highlights
- Two lava-tube caves formed by Mount Fuji's 864 CE Jogan eruption
- Ice pillars and icicles inside Narusawa Ice Cave that persist through summer
- Fugaku Wind Cave's history as a natural cold-storage facility for silkworm eggs
- Near-constant 0°C (32°F) cave temperatures offering summer relief from the heat
- Combined discount ticket covering both caves
Tips for visiting
- Bring a jacket even in summer, as both caves stay near freezing regardless of outside temperature
- Wear closed, non-slip shoes, since cave floors can be wet and Narusawa Ice Cave involves ladders and low passages
- Buy the combined ticket if visiting both caves, as it is cheaper than paying separately
- Visit Narusawa Ice Cave first if pressed for time, as it has the more dramatic ice formations
- Avoid the caves if uncomfortable in tight, low-ceilinged spaces, particularly at Narusawa
When to visit
Summer, for the cool relief and thickest seasonal ice formations built up from the preceding winter.
Accessibility
Fugaku Wind Cave's main route is relatively level but uneven underfoot, while Narusawa Ice Cave involves ladders, low ceilings, and narrow single-file passages that are not accessible for wheelchair users.
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Frequently asked questions
How long does a visit take?
Each cave takes about 20 to 30 minutes to walk through; visiting both takes roughly 45 minutes to an hour and a half including the short transfer between them.
Is it worth it for kids?
Older children generally enjoy the caves' cold air and ice formations, though the low passages and ladders at Narusawa Ice Cave can be difficult for very young children.
Is photography allowed?
Photography is permitted inside both caves, though flash can be limited in narrow sections to keep foot traffic moving.