Everyone is familiar with the beauty of Mount Fuji. We have all seen stunning pictures of its beauty, or been lucky enough to visit it in person. We often think of Mount Fuji as an icon, a beautiful symmetrical cone to view, or climb. The history of Mount Fuji and its creation is actually more interesting than that. Along with the creation of the five great lakes, Mount Fuji’s eruptioin also created several caves!
The current Mount Fuji that we see today is actually an accumulation of three separate eruptions. Around 100,000 years ago where Mount Fuji now stands, was Komitake Volcano. Nearby along this joining of tectonic plates, were Ashitaka and Hakone Volcano. Then 50,000 years ago Komitake volcano erupted, and formed the new stratovolcano of Ko-Fuji (Old Fuji). Between the last 17-10,000 years, Ko-Fuji erupted again. This time, it created Shin-Fuji (New Fuji). Since then Mount Fuji has erupted several times, which have all added to the current shape of the mountain we see today.
Caves are often formed during volcanic eruptions. This is due to the action of the lava that flows from the volcano. When the lava is flowing gas bubbles can form. When these gas bubbles burst through the cooling lava, caves are formed. Several caves were formed around the Mount Fuji area; the most attended and popular of these are the Ice Cave and the Wind (or Lava) Cave.
Narusawa ice cave is located near Lake Sai in the great lake region of Mount Fuji. This cave is very special. Even in the heat of summer the temperature in the cave is 0 degrees! So, when it is 32 degrees plus outside, the cave is 32 degrees colder! This means that in the winter it is very, very cold indeed. It is called the ice cave because naturally forming ice columns can be seen inside. The water from the forest above drips down into the cave, forming ice pillars which can get to 3 feet in height. In the Edo period, ice was kept here for the government officials!
Not far away is the Wind (lava) cave. Much similar to the ice cave it is colder in here all year round. This cave was used to store food, such as rice, and also silkworm cocoons.
Both of these caves cost 350 yen each to enter, but a joint ticket can be purchased. If you visit make sure you have good footwear, as it can be slippery in the caves. Also, mind your head!