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Cinnamon Land
🎲
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.

🐿️ Cinnamon was here

Field report

Lake Akan grows marimo: rare, velvety green algae balls that roll gently along the lakebed until, over centuries, they become perfect spheres — some the size of soccer balls. They have their own protection law, their own festival, and their own gift-shop empire of tiny jarred imitators.

I took the boat across the caldera lake to the observation center where the big marimo live in tanks like sleeping planets. I pressed a paw to the glass. They did not react. Three hundred years old and above small talk — I respect it completely.

The lake sits in Ainu country, and the village on the shore is one of the best places to encounter living Ainu culture and carving. Winter freezes the lake into another world entirely. Go for the algae, stay for everything the algae never told you about.

— Cinnamon 🐿️

📸 Cinnamon's camera roll

Snapshots from our very good boy on the road.

Paw to the glass with the big marimo — sleeping planets, three hundred years old and above small talk. I respect it completely.
The boat across the caldera lake. Mon-chan met an algae ball rounder and fluffier than him and needed a moment at the railing.
Lake Akan (marimo home lake)
Photo via Wikimedia Commons
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!
🌲 Nature 🏷️ Lake 🏷️ Marimo 🛸 Oddity 💎 Hidden Gem 🧒 Kids 📷 Photography

Where it is

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