Lake Mashu: Hokkaido's Lake of Mist
How to see Lake Mashu, one of the clearest lakes in the world: the viewpoints, why it is often hidden by fog, winter visits and getting there.
Quick answer
- What it is: a caldera lake in Akan-Mashu National Park in eastern Hokkaido.
- Famous for: its deep blue colour, remarkable clarity and frequent mist.
- Viewing: seen only from viewpoints on the rim, as there is no access to the shore.
- Time needed: 1 hour, or a full day with nearby lakes and hot springs.
- Best time: clear mornings, or winter for frozen scenery.
Lake Mashu sits deep inside a volcanic crater, its water an intense blue. It is famous for being hard to see, as mist often rolls in and hides it completely. Locals say that if you see it clearly, your luck may suffer.
Why Lake Mashu is a wonder
Lake Mashu has no rivers flowing in or out. Fed mainly by rain and snow, it has long been one of the clearest lakes in the world.
Its steep crater walls drop straight to the water, and visitors are not allowed to the shore, which helps protect it.
The lake of mist
Cool air from the Pacific often fills the crater with fog, especially in summer. Some days the lake is a sea of white clouds, which can be just as beautiful.
In winter, frost coats the trees on the rim, and the frozen lake glows under clear skies.
Nearby sights
| Spot | What you see | Distance (approx.) |
|---|---|---|
| Mashu No. 1 Observatory | The main viewpoint with a rest house | On the rim |
| Mashu No. 3 Observatory | A quieter view over the lake | About 3 km along the rim |
| Mount Io | A steaming sulphur mountain | About 15 km |
| Lake Kussharo | A large lake with hot sand beaches | About 25 km |
| Kawayu Onsen | A hot spring village | About 15 km |
When to go
- Early morning: the best chance of a clear view.
- Summer: green forests, but often foggy.
- Autumn: colourful leaves on the crater walls.
- Winter: frost-covered trees and a frozen lake.
Our tip: If the lake is hidden in mist, wait 20 to 30 minutes. The fog often shifts and the lake can appear quite suddenly.
Getting there
- By car: drive from Kushiro or Memanbetsu airports, about 1.5 to 2 hours.
- By train: take the JR Senmo Line to Mashu Station, then a seasonal bus or taxi.
- Tours: sightseeing buses link Lake Mashu, Mount Io and Lake Kussharo in season.
Visiting tips
- Stay behind the fences at the viewpoints.
- Roads to the rim can be icy or closed in winter.
- Bring warm clothes, even in summer.
- Do not leave food outside, as wildlife lives nearby.
Frequently asked questions
Why is Lake Mashu often foggy?
Cool, moist air often fills the crater, especially in summer.
Can you walk down to Lake Mashu?
No. It can only be viewed from the rim.
How clear is Lake Mashu?
It is one of the clearest lakes in the world.
When is the best time to see Lake Mashu?
Early mornings, and clear winter days.
Kawagoe
Black clay warehouses and an old wooden bell tower, half an hour from Tokyo.
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