Narusawa Ice Cave and Fugaku Wind Cave: Mysterious Caves Born from Mt. Fuji's Lava

Narusawa Ice Cave and Fugaku Wind Cave are mysterious lava caves born of Mt. Fuji eruptions. Spreading underground beneath the Aokigahara sea of trees, these caves open into another world wrapped in ice and cool even in summer. Once used as natural refrigerators, their interiors are filled with mysterious ice formations. They are popular attractions unique to the foot of Mt. Fuji, where you can feel the workings of the earth firsthand.

Highlights

Caves Born of Mt. Fuji Eruptions

Narusawa Ice Cave and Fugaku Wind Cave are lava caves formed by the lava flow of the great Jogan eruption of Mt. Fuji in the year 864 during the Heian period. As the surface of the flowing lava cooled and hardened while the still-hot lava inside drained away, cavities remained and the caves took shape. Located underground in the Aokigahara sea of trees on the northern foot of Mt. Fuji, they were designated National Natural Monuments in 1929, a precious presence that lets you feel the dynamic workings of the earth up close.

The Ice World of Narusawa Ice Cave

Narusawa Ice Cave is a vertical ring-shaped cave about 156 meters in total length. The average annual temperature inside stays around 3 degrees Celsius. Its ice-covered appearance even in summer is truly mysterious, with icicles formed by water seeping and freezing from the ceiling and pale-blue glowing ice walls creating a fantastical world. The natural cold was once used to store silkworm eggs and food as a natural refrigerator. There are low, narrow passages where you must stoop, adding a thrill of exploration.

Highlights of Fugaku Wind Cave

Fugaku Wind Cave is a horizontal cave and a popular spot alongside Narusawa Ice Cave. About 200 meters in total length, its interior is relatively spacious and easy to walk. It too stays cool year-round, wrapping visitors in chilly air even in summer. It was once used to store silkworm eggs and seeds. Highlights abound, including lava shelves that mark the passage of the flow and icicles that shine by reflecting light. Known too for muffling sound, it lets you experience the wonders of nature.

Seasonal Highlights

The caves are cool year-round, but the large temperature gap with the outside makes summer (July to August), when people seek relief from the heat, especially popular. In winter the ice formations grow more elaborate, showing a mysterious appearance. In the fresh-green and autumn-foliage seasons, pairing a visit with a walk in the Aokigahara sea of trees is also recommended. Since the interior is cold all year, bringing a layer to put on is reassuring even in summer.

Access and Basic Information

For access, take a bus from Kawaguchiko Station on the Fujikyu Railway line to each cave; Narusawa Ice Cave is about 25 minutes away. By car it is about 15 minutes via National Route 139 from the Kawaguchiko Interchange on the Chuo Expressway, and parking is available. The two caves are close together and can be visited on one trip. Because the caves are narrow with stairs and steps, sturdy walking shoes are essential. Check admission fees and hours in advance with the operator to be safe.

Practical Travel Notes

The best season is summer, when the temperature gap with the outside feels pleasant, though summer weekends and the Obon period get crowded, so an early-morning visit is recommended. Allow about 15 to 20 minutes to view each cave, and one to two hours for both. Since the interiors are slippery with low ceilings in places, wear easy-to-move clothing and sneakers. Nearby attractions include the Fuji Five Lakes, the nature trail through the adjacent Aokigahara sea of trees, and Lake Sai, which round out a tour of the Mt. Fuji foothills. Budget-wise, admission is a few hundred to around a thousand yen.

A Word of Advice

Narusawa Ice Cave and Fugaku Wind Cave offer an extraordinary experience of an ice world even in summer. The interiors are chilly and the footing gets wet, so do not forget a layer and non-slip shoes. Those uneasy with heights or with dark, narrow passages should enjoy within their comfort. Take your time savoring the natural forms that Mt. Fuji created over long ages.

📚 Sources

This article draws on the official guidance of the operator of the Narusawa Ice Cave and Fugaku Wind Cave, published materials on the National Natural Monument, and information on the Aokigahara forest nature trail. Cave admission, opening hours, and car-park conditions can change with the season and operations. Since fees and times may change, please confirm the operator's official information before you visit.

Visitor Checklist

• Estimated time: About 15 to 20 minutes per cave, or one to two hours for both.
• What to prepare: The caves are narrow with steps, so wear easy-moving clothes and trainers.
• Clothing tip: The interiors stay cold all year, so bring an extra layer even in summer.
• Avoiding crowds: Summer weekends and the Obon period are busy, so arrive early.
• Nearby stops: Combine with the Aokigahara nature trail beside Fugaku Wind Cave and the Fuji Five Lakes.