Akan-Mashu National Park

Non-profit Nature Service http://www.natureservice.jp/

A vast landscape comprising Japan's largest caldera landform, volcanoes, forests and lakes

Venture off the beaten path, deep into the island of Hokkaido. Travel between the park’s caldera lakes of Kussharo, Akan and Mashu, explore primeval forests and relax in hot springs. In the long snow season, the landscape transforms into a winter wonderland. Home to settlements of indigenous Ainu people, this national park offers endless cultural discovery. Read more about Akan-Mashu National Park.

Lake Onneto

Visiting Japan's National Parks

Akan-Mashu National Park, like all of Japan's national parks, has no entrance fees, no opening and closing hours, and a permit is not required to enter or stay in the park. The national parks of Japan differ from national parks worldwide in that the land within the national parks is not exclusively designated for national park use and is made up of private property as well as public and protected areas. Visitors are free to enter and leave at any time.

Park Highlights

Perhaps the greatest allure of Akan-Mashu National Park is the cherished landscape characterized by three caldera lakes—Kussharo, Akan and Mashu—the beauty of the park's volcanoes, and primitive, primarily subarctic coniferous forests.


  • Marimo—very rare spherical lake algae found in only a few other places on Earth
  • Hiking up Mt. Me-akan to see the volcanic vents
  • An Ainu cultural performance at Lake Akan Ainu Theater Ikor

Mt. O-akan and Mt. Me-akan rise serenely in the background of Lake Akan and Lake Onneto. The pristine Lake Mashu is famous as one of the world's clearest lakes, and a beautiful view of Lake Kussharo awaits from the surrounding mountains. Kaminoko Pond is steeped in a mystic aura and the ever-changing forest scenery impresses in every season.


Lake Kussharo is Japan's largest caldera lake. In winter, the lake freezes over completely and ice-pressure ridges of over 10 kilometers can form on the surface ice. In local tradition, these ridges are attributed to gods crossing the lake.

Lake Kussharo


Lake Akan is situated on the west side of the Akan caldera and is famous as a habitat for marimo. Visitors can take a trip across the lake in a tour boat, enjoy fishing, and bathe in nearby hot springs.

Lake Akan as viewed from Mt. O-akan


The Mashu Caldera was formed approximately 7,000 years ago by an enormous volcanic eruption. Inside the caldera is Lake Mashu, which is one of the most transparent lakes in the world. It is known for the thick fogs that frequently occur above the lake's surface, creating a mysterious atmosphere. On the southwestern side of the caldera is Mt. Nishibetsu, a treasure trove of alpine plants.

Mashu Caldera


Mt. Me-akan is located to the southwest of Lake Akan. This volcano remains active to this day. Near the peak, visitors can view the volatile crater and the volcanic gases rising from it.

Mt. Me-akan


Located on the southern shore of Lake Akan, Akanko Onsen is lined with large hotels and makes for a good base for a wide range of sightseeing activities. Visitors can see marimo and bokke bubbling mud or take a sightseeing cruise in warmer months. In winter, enjoy skiing in the mountains and skating on the lake.


The largest Ainu settlement in Hokkaido, Ainu Kotan is located in the Akanko Onsen hot spring district. At the Lake Akan Ainu Theater Ikor, visitors can watch a traditional Ainu dance that has been designated an Intangible Cultural Heritage by UNESCO.


In the past, Mt. Iwo was mined for sulfur. The mountain has more than 1,500 vents, both large and small, from which white plumes of gas constantly rise.

Mt. Iwo

Plants & Animals

Akan-Mashu National Park's vast forests, lakes and reservoirs are the foundation of its ecosystems. Mixed forests of conifers and broad-leaved trees comprising mainly Sakhalin fir and Yezo spruce exist alongside pure forests of Sakhalin spruce (Picea glehnii). Rare marimo algae balls form in Lake Akan, while isotsutsuji flowers grow in abundance around Mt. Iwosan.

Animals that live in the park include Yezo deer, brown bears, Ezo red foxes, raccoon dogs and Japanese sable. Birds such as goldcrests, coal tits, great woodpeckers and great spotted woodpeckers live in the coniferous forests, while large grey herons and various duck species reside around the lakes and reservoirs.


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    Isotsutsuji (Ledum Palustre var. diversipilosum)—a relative of the rhododendron—grow in large numbers around Mt. Iwosan due to the impact of fumaroles, openings in areas surrounding volcanoes that emit sulfurous gases. These flowers grow in Hokkaido and subalpine and alpine areas of Honshu.

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    Marimo is a species of freshwater green algae found in a number of lakes in Hokkaido and Honshu. The marimo that grow in Lake Akan have been designated a National Special Natural Monument due to their beautiful spherical shape.

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    Ezo Red Fox 


    The Ezo red fox can be spotted in various areas of Akan-Mashu National Park. It is a subspecies of the red fox, which is commonly found across the entire northern hemisphere.  

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    Yezo Deer


    The forest zones of Akan-Mashu National Park are an important habitat for the Yezo deer. The indigenous Ainu people of Hokkaido have relied on them as a major food source for centuries.



There are numerous communities of Ainu, an indigenous people of northern Japan, dotted around Hokkaido. The 30-household-strong Ainu Kotan (Ainu village) is located on the west side of Akanko Onsen Town and is the largest Ainu community in Hokkaido. Traditionally, the Ainu people venerate the bear as the manifestation of a high-ranking mountain god who descends from his heavenly kingdom to visit Earth. 


Ainu dress and dugout canoe


Iomante is a ritual performed by the Ainu people to send the spirit of the mountain god back to his kingdom. During the Iomante Fire Festival, it is possible to see traditional dances and rituals, such as the fire-lighting ceremony conducted by Ainu elders. Today, performances of the Iomante Fire Festival are held at the Lake Akan Ainu Theatre Ikor in May-June and September-November to enable visitors to experience Ainu culture. At the Ainu Folklore Museum on the shore of Lake Kussharo, you can encounter Ainu history and learn about the Ainu belief that all things—natural phenomena and inanimate objects included—are considered sacred beings.

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    Seasonal Information

    After the snow melts, local flowers start to bloom in earnest in May in Akan-Mashu National Park. Summer is pleasant, with daytime highs ranging between 20 to 30 degrees, and cool nights. It's the ideal time to go camping, kayaking or canoeing, and enjoy the outdoors.

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    Fall is a great season to go hiking and experience the fall foliage, but the chilly weather sets in from early October. In winter, Akan-Mashu receives a large amount of snow, and the lakes freeze over completely. Get a rare glimpse of migratory birds, join a snowshoeing tour, or take a walk on a frozen lake.

About the Park 

Akan-Mashu National Park is located in eastern Hokkaido and is one of the longest-established parks in the Hokkaido region.


  • Date of National Park Designation: December 4, 1934
  • Area: 91,413 ha (914.13 square kilometers)
  • Location: Hokkaido


In addition to housing interactive displays of the area's ecology and wildlife, the Akankohan Eco-museum Center and the Kawayu Eco-museum Center provide information about the park, hiking trails, weather and things to do in the surrounding area. The Akanko Marimukan near the shore of Lake Akan is a good stop for park maps and sightseeing pamphlets, as well as information about the greater eastern Hokkaido region.


As with any national park or conservation area, visitors to the national parks are required to observe the following rules for safety and to protect the area's natural biodiversity:

  • Carry in, carry out: Take all of your trash with you. 
  • Do not pick wildflowers or damage plants. 
  • Do not feed the wild animals. 
  • Hunting is not permitted. 
  • No fishing unless with a certified guide.
  • No smoking while walking. 
  • Campfires are only permitted in designated areas. 
  • Stay on the footpaths and hiking trails.
  • Do not approach wildlife.