Lake Mashu (摩周湖) in Akan National Park (阿寒国立公園) located in the eastern part of Hokkaido (北海道) is known as one of the world's clearest, most transparent lakes.
It is a crater lake formed about 7,000 years ago by a large volcanic eruption. The lake is surrounded by a steep wall which forms at one point in the western part a 300 meter high sheer cliff. In the centre of the lake is a small island called Kamuisshu meaning "an old woman who became a god" in the Ainu language. The island is actually the summit of a lava dome rising from the middle of the lake.
Lake Mashu has a circumference of 19.8 km, an elevation of 355 m above sea level, and its maximum depth is 211.5 m. With no significant incoming or outgoing streams, it is believed that the water seeps out through the porous bottom sediments, for the water level remains almost constant.
Since ancient times the lake has been worshipped by the Ainu people as the "Lake of the Gods". Its emerald-green crystal clear surface changes its expression moment by moment. However, the lake can be rarely seen in summer due to the heavy mist. This is why the lake received a reputation of a mysterious lake. It really is associated with many mysteries and legends.
According to the transparency survey carried out in 1931, Lake Mashu's underwater visibility of 41.6 m was said to be the highest in the world, even surpassing that of Lake Baikal in Russia. With the increasing development in the surrounding area, however, and also because of the later introduction of sockeye salmon and rainbow trout into the lake, the transparency has decreased year after year.
Due to the
heavy mist it is prohibited to enter the lakeshore area, and visitors can view the lake only from the designated observation towers. 霧の摩周湖
布施明
Once being so isolated, Lake Mashu was rarely visited by tourists, but since the song "Misty Lake Mashu" by a famous Japanese singer Akira Fuse (布施明) hit the charts in 1966, the lake has been an
increasingly popular tourist spot.
By the way, the singer was once married to the actress Olivia Hussey who played the title role in the film "Romeo and Juliet" (1968).
From the film "Romeo and Juliet"