Reaching a height of 6,040 feet, Mount Zao is one of the most prominent mountains in the Tohoku Region. This active volcano features a beautiful crater lake known as Okama Crater Lake.
Okama Crater Lake is considered to be one of the world’s most beautiful crater lakes. Situated in the caldera of Mount Zao, it is surrounded by 155 square miles of protected landscape which forms the Zao Quasi-National Park. The lake is referred to as Goshiki Numa meaning five-color pond. The highly acidic and mineral laden lake changes colors in conjunction with prevailing weather conditions. The lake has a 20 acre surface area and is reported to be 90 feet deep. The colors are best observed during the summer months as the lake tends to freeze during the winter.
A caldera is a cauldron-like volcanic feature that is formed when a magma chamber is emptied. Mount Zao’s caldera was created in the 1720s when the volcano erupted. Although currently dormant, Mount Zao is the most active volcano in northern Honshu. However, this does not stop the droves of visitors that visit the area annually.
The Zao Quasi-National Park is a very popular hiking destination split into three areas: North, Middle and South. The main hiking area, the ski area and Okama Crater Lake are located in the Middle section. Although the lake is not directly accessible due to the active fumaroles that emit noxious gases, many visitors do hike to the rim of the crater. There is a designated viewing point which affords ample photo opportunities as well as a ski lift allowing visitors to observe the lake from above.
The lake is accessible via the Yamagata Shinkansen exit at Kaminoyama Onsen Station. From that point there are two buses which operate twice a day and are free of charge! The one way trip requires approximately one hour.