Akan Mashu National Park
Park Hokkaido national park with caldera lakes and wildlife
Akan Mashu National Park in eastern Hokkaido protects caldera lakes-Akan, Mashu and Kussharo-and the rare marimo algae. Tourists arrive for lake-side hiking, onsen towns, Ainu cultural centers and boat trips across glass-clear volcanic waters.
Akan Mashu National Park is a protected area on eastern Hokkaido centred on a volcanic caldera region that contains several notable lakes and volcanic cones. The park conserves freshwater lakes, volcanic landforms and mixed forest ecosystems and is a major nature destination in Hokkaido.
Scenic caldera lakes, volcanic peaks and hot spring areas; popular activities are lakeshore walks, wildlife viewing and hikes up volcanic cones such as Mount Meakan. Lake Akan is particularly known for marimo, rare spherical algal formations that attract visitors and conservation interest.
The park was designated in the early 20th century as part of Japan’s national park system to protect the Akan volcanic area and its lakes, and it has since been managed for both conservation and public access. Facilities and trails have been developed at key lakeside and onsen settlements to support tourism while protecting sensitive natural features.
Located in eastern Hokkaido, the park lies within the island’s volcanic plateau region and is accessed from towns such as Kushiro and Akan Onsen; the area is remote compared with Hokkaido’s main population centres and is reached by road from nearby regional hubs.
- Designation: The park was one of Japan's earlier national parks, designated in the 1930s and centred on a volcanic caldera region with several notable lakes.
- Marimo: Lake Akan is famous for marimo, a protected form of filamentous algae that forms green spherical clumps and is a local conservation focus.
What to See #
- Lake Mashu: A deep, caldera-formed lake famous for very clear water and scenic cliffs; access is via viewing points and walking trails on the caldera rim.
- Lake Akan: A volcanic lake known for the presence of marimo - rare spherical algae - and a long-established onsen resort area on its shores.
- Lake Kussharo: A large caldera lake that forms part of the park's core water systems and supports lakeshore trails and campsites.
- Mount Meakan: An active volcanic cone within the park that supports hiking trails and offers volcanic landscapes and panoramic views over the lakes.
Tips for Visiting Akan Mashu National Park #
- For the famed clarity of Lake Mashu, visit the main observation decks at first light when mist is least likely to obscure the crater lake-clear mornings give the best views.
- Plan transport around seasonal public buses and boat services; many vantage points and trailheads within Akan Mashu National Park have limited or seasonal road access, so check bus timetables from Kushiro/Akan and reserve transfers in advance.
- Don't miss Lake Akan's marimo exhibits and conservation displays near the lake's visitor facilities-these explain the local ecology and are good context before hiking or boating in the area.
Best Time to Visit Akan Mashu National Park #
Late spring to early autumn (June-October) is best for accessing Akan Mashu National Park; winter brings heavy snow and limited access.
Weather & Climate near Akan Mashu National Park #
Akan Mashu National Park's climate is classified as Warm-Summer Continental - Warm-Summer Continental climate with mild summers (peaking in August) and freezing winters (coldest in January). Temperatures range from -12°C to 22°C. Abundant rainfall (1115 mm/year), wettest in September.
January
January is the coldest month with highs of -4°C and lows of -11°C. Moderate rainfall (58 mm) and partly cloudy skies.
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February
February is the coldest month with highs of -4°C and lows of -12°C. Moderate rainfall (48 mm) and partly cloudy skies.
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March
March is freezing with highs of 0°C and lows of -7°C. Regular rainfall (81 mm) and mostly overcast skies.
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April
April is cold with highs of 7°C and lows of 1°C. Regular rainfall (80 mm) and mostly overcast skies.
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May
May is cold with highs of 13°C and lows of 5°C. Regular rainfall (98 mm) and mostly overcast skies.
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June
June is cool with highs of 16°C and lows of 10°C. Regular rainfall (87 mm) and mostly overcast skies.
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July
July is cool with highs of 20°C and lows of 14°C. Regular rainfall (100 mm) and mostly overcast skies.
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August
August is the warmest month with highs of 22°C and lows of 16°C. Significant rainfall (135 mm) and mostly overcast skies.
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September
September is cool with highs of 19°C and lows of 12°C. The wettest month with heavy rain (161 mm) and mostly overcast skies.
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October
October is cold with highs of 14°C and lows of 6°C. Significant rainfall (118 mm) and partly cloudy skies.
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November
November is cold with highs of 6°C and lows of -1°C. Regular rainfall (90 mm) and partly cloudy skies.
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December
December is freezing with highs of 0°C and lows of -7°C. Moderate rainfall (59 mm) and partly cloudy skies.
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