Skip to content
Roadside Japan
🎲
Lake Akan Marimo
🛸 Oddity

Lake Akan Marimo

📍 Hokkaido, Kushiro

A clear caldera lake in eastern Hokkaido that grows one of the world's strangest treasures: marimo, rare velvety-green balls of algae that roll along the lakebed and have their own festival — and mascot.

In the clear water of Lake Akan, deep in eastern Hokkaido, grows something that sounds invented: marimo, soft spheres of green algae that form naturally into velvety balls and roll gently across the lakebed. Akan is one of the very few places on Earth where they grow this big and this round.

Why It’s Interesting

A ball of algae shouldn’t be this charming, yet marimo are beloved enough to have a mascot, a festival, and protected-treasure status. The largest can reach the size of a soccer ball, taking decades to grow. You can meet them up close at the Marimo Exhibition Center on a little island in the lake, reached by sightseeing boat, and the lakeside hot-spring town leans all the way into the green-pompom theme.

Best Time to Visit

Year-round. Summer is easiest for the boat; autumn brings the Marimo Festival; and in deep winter the whole lake freezes solid for ice fishing and frost-flower viewing.

Getting There

It’s remote — buses run from Kushiro to Akanko Onsen on the lakeshore. Take the sightseeing boat out to see the real marimo, and leave them where they are.

📸 Mon-chan's camera roll

Snapshots from our very good boy on the road.

Close-up of fuzzy round green marimo algae balls resting underwater
They're balls. Of algae. That roll around. I am obsessed.
Mon-chan and Cinnamon the squirrel cradling a fuzzy green marimo ball
A fuzzy green ball, smaller than me, so I allowed it. Cinnamon: chk-chk!

Where it is

You might also like

Nearby discoveries

Comments

  • No comments yet — be the first to share a tip.

Leave a comment

Share a tip, a correction, or what you saw. Comments are reviewed before they appear — no account needed.