Natural spring water
There is a lot of underground water around Mt. Fuji, which is the highest mountain in Japan. One of the best known among them is the Kakita River natural springs in Mishima City, Shizuoka Prefecture. Rainwater that has fallen on Mt. Fuji is filtered by the bedrock of the mountain over a period of 10 years and springs out in Mishima. I've always wanted to go to the Kakita River, and I was finally able to actually make a visit the other day. There is a park around the river, and visitors can observe the spots where water is springing out from several observation docks. I was particularly impressed by the remains of an old well used by a paper company in the past. The well is approximately 3m in diameter and 3m deep. The bottom of the well is covered by sand, and from a few spots clear water gushing out to whip up the sand. When the sun shines in, the water turns blue, which is very mysterious.
Mishima is also famous for eels. There are many eel restaurants in the town because highly purified spring water can remove excess fat from eels, making them delicious. I didn't get the chance to have eel during the last trip, but I'd definitely like to try next time.