Mashu volcano erupted some 7,000 years ago and created the Mashu Caldera that has collected water for some 3,000 years. That was the beginning of Lake Mashu. The current shape of the lake was formed/created about 1,000 years ago when Mt. Mashu erupted for the last time.
The deep, clear water of Lake Mashu is world class known for its transparency. We call the color of the water “Mashu blue” which changes depending on the season, time and weather. There are no rivers flowing in or out of the lake. There are no paths going down to the lake, and entering the lake is strictly prohibited.
We consider it the most beautiful of all Japan’s lakes, and we are quite sure that you will discover it is a very special place when you visit there.
There is a trail going up to Mt. Mashu where you can enjoy a spectacular view of the lake from different angles, that starts from Lake Mashu Observation Deck No.1. You’ll enjoy alpine flowers on the way to the summit in summertime.
