Lake Akan
Lake Caldera lake in Hokkaido noted for marimo algae
Lake Akan in Hokkaido sits inside Akan National Park; tourists come for boat rides to see marimo moss balls, lakeside onsen towns, Ainu cultural centers and nearby hiking.
Lake Akan is a caldera lake in Akan National Park on the island of Hokkaido, Japan. It is best known for its marimo, the rare spherical green algae that occur naturally in the lake and nearby waters.
The lake is a regional recreational centre with boat cruises, shoreline walking routes and hot-spring resorts on its shores. Visitors come for marimo observation, short cruises across the water and to use nearby onsen facilities that serve as bases for lake access.
The lake occupies a volcanic basin formed by eruptions and lava flows from surrounding volcanoes; its present shoreline and islands are the result of that volcanic activity. Protection measures focused on the marimo colonies and surrounding parkland have been in place for decades.
Lake Akan lies in eastern Hokkaido within Akan National Park, on the interior of the island rather than the coast. The nearest larger urban centres in eastern Hokkaido serve as access points for visitors to the park.
- Marimo colonies: Home to one of the few natural populations of marimo, the rare spherical colonies of Aegagropila algae that are protected as a natural monument in Japan.
- Access and seasons: Accessible year-round with seasonal highlights in autumn foliage and winter ice - boat services and short cruises operate in the warmer months.
What to See #
- Akanko Onsen: Onsen town on the lake shore that serves as the main gateway for cruises, marimo viewing and boat excursions.
- Marimo exhibition centre: Small exhibition and observation facilities that explain and display the lake's marimo colonies and local ecology.
How to Get to Lake Akan #
From Kushiro Station you can reach Lake Akan (Akan-ko) by highway bus operated toward Akanko Onsen; the ride takes about 1.5-2 hours. By car it’s roughly an 80 km drive from Kushiro along National Route 240 and local roads (about 1.5 hours); there is short walking access from the Akanko Onsen bus stop or parking area to the lake shore (a few minutes).
Tips for Visiting Lake Akan #
- Head to the Akan-ko (Akan Onsen) area and visit the Marimo Exhibition and Research Center - short sightseeing boat cruises from the Akan-ko pier are the most reliable way to see marimo colonies close up.
- To avoid day-trip tour crowds, aim for the first boat in the morning or later afternoon; the onsen town around the lake is the main arrival point for buses and gets busiest in mid-day.
- Autumn is a popular time for foliage around Lake Akan (peak typically in October), so expect more visitors then and book any boat tours and accommodation in advance.
Best Time to Visit Lake Akan #
Best from late spring through early autumn (May-October) for mild weather, easy access and scenic views.
Weather & Climate near Lake Akan #
Lake Akan'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 -15°C to 22°C. Abundant rainfall (1248 mm/year), wettest in September.
January
January is the coldest month with highs of -6°C and lows of -15°C. Moderate rainfall (71 mm) and partly cloudy skies.
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February
February is freezing with highs of -6°C and lows of -15°C. Moderate rainfall (58 mm) and partly cloudy skies.
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March
March is freezing with highs of -2°C and lows of -10°C. Significant rainfall (107 mm) and mostly overcast skies.
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April
April is cold with highs of 6°C and lows of 0°C. Regular rainfall (88 mm) and mostly overcast skies.
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May
May is cold with highs of 12°C and lows of 5°C. Significant rainfall (104 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 (86 mm) and mostly overcast skies.
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July
July is mild with highs of 21°C and lows of 15°C. Regular rainfall (96 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 (141 mm) and mostly overcast skies.
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September
September is cool with highs of 18°C and lows of 11°C. The wettest month with heavy rain (173 mm) and mostly overcast skies.
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October
October is cold with highs of 12°C and lows of 5°C. Significant rainfall (136 mm) and partly cloudy skies.
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November
November is cold with highs of 6°C and lows of -2°C. Significant rainfall (115 mm) and partly cloudy skies.
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December
December is freezing with highs of -1°C and lows of -9°C. Moderate rainfall (73 mm) and partly cloudy skies.