Lake Akan Lake

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.

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).

• 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.