Mashu-ko, Mashu-dake and Io-zan

By Paul S Bryers, September 2016

If you are based in Lake Kussharo or Teshikaga area you can spend a very rewarding day viewing Lake Mashu, climbing Mount Mashu and visiting sulphurous Mount Io. 

Lake Mashu is one of Japan’s most beautiful lakes. Formed following an enormous eruption that resulted in a huge caldera, Lake Mashu has precipitous sides and is towered over on the East side by Mount Mashu. In the center of the lake is the tiny Isle of Gods, the result of a volcanic plug within the caldera.

Start your day at Parking spot #1 off Route 52; the latter winds its way past the West rim of the caldera. The views of the lake and mountains are stunning. Then take the Mount Mashu trail and head East. On the way you will get great views of the surrounding mountains, as well as the birch forests rising out of the endless bamboo groves. It takes about 2.5 hours to get to the peak of the mountain, with the last 400 m being steep but manageable – just don’t look to your right and definitely not to your left. The views of the lake are terrific – the views into the secondary caldera of the mountain are terrifying.







It takes about 2 hours to get back to the parking area. Get back onto Route 52 and go North. Mount Io is about 8 miles away. It’s a little disappointing compared to the easily accessible volcanic areas in Iceland and New Zealnd, but it is every bit as smelly (sulphurous). Still, worth the visit as you are in the area anyway. The take Route 52 back to Lake Kussharo – you might want to visit one of the free hot springs on the way.

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