The most distinctive feature of Lake Mashu is its transparency. The water in the lake is so clear that it reflects very little light other than blue, and the color of the lake's surface on a clear day is called "Mashu Blue." The lake is also surrounded by steep walls, making it impossible to go down to the lake surface.

Lake Mashu is also known as "Misty Lake Mashu" due to its mysterious atmosphere. Fog is particularly common in the summer, and the entire lake can be enveloped in a fantastic veil. This fog further accentuates the mysticism of Lake Mashu, and while a clear day is nice, Lake Mashu shrouded in mist also has a special charm. In the center of the lake, there is a small island called Kamuishu Island, which adds to the mysticism of the lake.

There are several observation decks on the lakeside, where you can enjoy the view of Lake Mashu from various angles. The first observation deck is the easiest to access, and is equipped with a shop and a rest area.

[Hidden gem]
The first observation deck (parking fee required) is popular and crowded, but the third observation deck (parking free) is located further back from the first observation deck and is a hidden gem where you can quietly enjoy the magnificent view of Lake Mashu. Also, the "Ura Mashu Observatory" on the east side of Lake Mashu allows you to view the lake from a different angle than the first observation deck, and there are relatively few tourists, so you can enjoy the view at your own pace.