, also Kamuinupuri or Mount Mashū, a potentially active volcano, is a parasitic stratovolcano

Stratovolcano

A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...

 of the Mashū

Lake Mashu

is a landlocked endorheic crater lake formed in the caldera of a potentially active volcano. It is located in Akan National Park on the island of Hokkaidō, Japan. The lake has been called the clearest lake in the world.-Hydrology:...

 caldera

Caldera

A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...

 (itself originally a parasitic cone of Lake Kussharo

Lake Kussharo

is a caldera lake in Akan National Park, eastern Hokkaidō, Japan. As with many geographic names in Hokkaidō, the name derives from the Ainu language. It is the largest caldera lake in Japan in terms of surface area, and sixth largest lake in Japan. It is also the largest lake in Japan to freeze...

) located in the Akan National Park

Akan National Park

is a national park located on the island of Hokkaidō, Japan. Along with Daisetsuzan National Park, these are the two oldest national parks in Hokkaidō. The park was established December 4, 1934....

 of Hokkaido

Hokkaido

, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...

, Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

.

Volcanism

Mount Kamui rose on the rim of 6 km-wide Mashū caldera, about four thousand years ago, after the collapse of Mashū

Lake Mashu

is a landlocked endorheic crater lake formed in the caldera of a potentially active volcano. It is located in Akan National Park on the island of Hokkaidō, Japan. The lake has been called the clearest lake in the world.-Hydrology:...

 volcano. Its last eruption took place about 1000 years ago.

Tourism

Hikers can follow a 7.2 km wooded trail to the peak of the mountain, walking along the ridge of the caldera, which is a 300-m vertical drop to the surface of the Lake Mashū

Lake Mashu

is a landlocked endorheic crater lake formed in the caldera of a potentially active volcano. It is located in Akan National Park on the island of Hokkaidō, Japan. The lake has been called the clearest lake in the world.-Hydrology:...

, offering spectacular views.