Lake Mashu
Lake Mashu is a caldera lake in Akan-Mashu National Park, in Teshikaga in eastern Hokkaido, ringed by cliffs and known as one of the clearest lakes in the world.
Cloud in the caldera, eastern Hokkaido
- Region
- Hokkaido
- Journeys
- One of our journeys
overview
A lake of deep blue in a crater of cliffs, appearing and vanishing in the mist.
Lake Mashu fills the crater of a volcano that collapsed some seven thousand years ago. Cliffs rise two to three hundred metres from the water on every side, no river flows in or out, and the lake is fed only by rain and snow, which is why its water is so clear. In 1931 a disc lowered into it was still visible at a depth of more than forty metres, a measurement that made it, for a time, the clearest lake ever recorded. It is more than two hundred metres deep, and its colour is a blue so dark it has its own name, Mashu blue.
No one may go down to its shore. The lake is seen only from the rim, from viewpoints on the road, and that distance is part of its spell. In the middle stands a single small island, Kamuishu, which Ainu tradition takes to be an old woman who waits there for her lost grandchild. Sea fog drifts in from the Pacific and fills the caldera, so the lake is often hidden and then revealed, and it has long been called the lake of mist.
Lake Mashu lies at the centre of a country of calderas. Lake Kussharo, the largest caldera lake in Japan, is a few minutes away, with the sulphur vents of Mount Io and the onsen of Kawayu between the two, and Lake Akan is an hour away by car.
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see and do
What to see at Lake Mashu
Lake Mashu Observatory No. 1
The main viewpoint on the south-western rim, with a terrace over the lake, its island and the cone of Mount Kamuinupuri on the far side.
Observatory No. 3
A smaller viewpoint a little further along the rim road, higher and closer to the water, with a wider view across the lake and out to Lake Kussharo behind.
Ura-Mashu Observatory
The quiet viewpoint on the eastern side of the lake, reached from Kiyosato, seen by far fewer visitors and looking back across the water to the rim.
Kaminoko Pond
A small spring pond in the forest north of the lake, fed by water believed to seep underground from Lake Mashu, so clear and blue that the fallen trees on its floor can be seen as if through glass.
Mount Io
A small volcano below the lake, known in Ainu as Atosanupuri, where yellow sulphur crusts the rocks around steaming vents. The vents can be seen at close range on a short level walk from the car park.
Lake Kussharo
The largest caldera lake in Japan, a few minutes from Lake Mashu, with a wooded island at its centre and Sunayu, a beach where hot water rises through the sand.
Kawayu Onsen
A small onsen village between Mount Io and Lake Kussharo, its strongly acidic springs fed by the volcano, with a free footbath at its centre.
Bihoro Pass
A pass on the western rim of the Kussharo caldera, with a view over the whole of the lake and its island and the mountains beyond.
experiences
The best of Lake Mashu
The lakes and volcanoes by car
A day between Lake Mashu, Mount Io and Lake Kussharo with a private driver, stopping at each viewpoint and coming back to the rim when the mist lifts.
An onsen at the end of the day
The springs of Kawayu and the ryokan of Lake Akan close the day in hot water, with dinner of the seafood of the eastern coast.
The blue of Kaminoko Pond
A short walk through the forest to a small pond of startling clarity, one of the loveliest and quietest places in eastern Hokkaido.
plan your visit
Lake Mashu on a journey through Japan
- How long to stay
- Half a day for Lake Mashu itself and a full day with Lake Kussharo and Mount Io, usually from a base at Lake Akan.
- Getting there
- About an hour by car from Lake Akan, about an hour and a half from Kushiro Airport and about an hour and a quarter from Memanbetsu Airport. Mashu Station on the Senmo Line lies in the town below.
- Pairs well with
- Lake Mashu sits between Lake Akan and Shiretoko, so it falls on the road through eastern Hokkaido, with Kushiro and its cranes to the south.Lake AkanKushiroShiretokoDaisetsuzan
journeys
Tours of Japan that include Lake Mashu
Open a journey below for its route, its dates and its price. On dates of your own, a Custom Tour of Japan can bring you here and anywhere else in Japan you would like to go.
questions
Lake Mashu: questions answered
Why is Lake Mashu so clear?
Because no river flows in or out: it is fed only by rain and snow within its caldera. In 1931 a disc lowered into it was visible at more than forty metres, then a world record.
Can you go down to the shore of Lake Mashu?
No. Access to the shore is not permitted, and the lake is seen only from the viewpoints on its rim, chiefly Observatory No. 1, Observatory No. 3 and Ura-Mashu.
Why is Lake Mashu called the lake of mist?
Sea fog from the Pacific often drifts in and fills the caldera, so the lake is hidden and revealed in turn. A popular song of the 1960s made the name famous across Japan.
How deep is Lake Mashu?
More than two hundred metres at its deepest, in a caldera formed by the collapse of a volcano some seven thousand years ago.
How far is Lake Mashu from Lake Akan?
About an hour by car, which makes it an easy day from the onsen ryokan of Lake Akan, together with Mount Io and Lake Kussharo.
Which Luxury Japan Travel journeys include Lake Mashu?
The Wild North Tour of Hokkaido visits Lake Mashu for the day. On dates of your own, a Custom Tour of Japan can include Lake Mashu too.
Can Lake Mashu be part of a private tour of Japan?
Yes. The Custom Tour of Japan is created around your party alone, on your dates, with your own Tour Director, and it can go anywhere in the country, Lake Mashu included. If you would rather travel independently, the Expert Japan Itinerary plans every day for you.
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Every place in Hokkaido
Lake Mashu, planned for you.
Tell us when you would like to travel and what draws you to Lake Mashu, and we will answer with the journey that suits you best: one of our published tours, a journey of The Private Collection, or a Custom Tour of Japan created around your party alone.