Located in Akan Mashu National Park is Lake Mashu, a caldera lake that is known to be the clearest lake in the world. According to Japan, it is considered to be the most beautiful lake. The caldera was formed around 7,000 years ago by a powerful volcano eruption. The small island in the middle is a 240-meter volcano. The lake is surrounded by a crater wall measuring 300 to 400 meters tall, with an average of 45 degrees.
The lake is one of the deepest lakes measuring at 212 meters deep and is appreciated for its clear blue water. The water contains no contaminants with a unique blue colored water, which is also known as "Mashu Blue". It is said that the water level never changes even when there is no water flowing in or out. The lake is famous for the thick fog that often blankets over the lake, but can reveal itself suddenly. Fog often rises particularly in June or July, and it is said that is you encounter fog there, you are unlucky as locals the god of the lake rules our life.
Located around the rim of the caldera to enjoy the views of the lake, there are two observation decks, since no visitors are allowed to go down to the lake. There used to be three observation decks, but Observation Deck 2 was closed to the public. Observation Deck 1 is the most popular, where you can also try the local delicacy with a variety of snacks offered and can purchase souvenirs. Observation Deck 3 lies along the western rim of the caldera and consists of two decks with unobstructed views onto the lake and Mount Mashudake.
The best way to visit the lake is by car, but some busses operate between Mashu Station and the lake during certain periods, as buses don't operate outside of those certain periods.
Lake Mashu gain worldwide fame for its transparency. In 2001, it is recognized as the heritage of Hokkaido. A crater lake surrounded by volcanoes, Lake Mashu appears to be a deep blue mirror with a sense of mystery. However, it is often permeated with fogMore
The bus will cover Mashu Lake, Lake Kussharo, and Lake Akan. The bus will stop at Kushiro Marsh Observatory, Lake Mashu first observatory, Mount Iwo, Lake Kussharo (Sunayu), and Lake Akan Osan for vistors to explore the attractions.More
We do provide half-day or full day trip. However, due to the high demand on tour guides during high season, the price is expensive. Instead, we recommend booking a private transfer service, and we can arrange a driver speaking simple English.More