Lake Toya

Toya is an almost perfectly circular caldera about ten kilometres across, formed by a collapse over a hundred thousand years ago, with a cluster of wooded islands in the middle and hot springs feeding the lake so that it does not freeze even in a Hokkaido winter. What makes it more than scenery is Usu, the volcano on its southern shore, one of the most active in Japan: it erupted in 1943 to 1945 pushing up an entirely new mountain, Showa-Shinzan, which is still there and still steaming, and again in 2000, when the town below was evacuated in time and no one was killed. The scars of the 2000 eruption - buried roads, a wrecked bridge, collapsed buildings - have been left in place as an open-air disaster museum. Toyako Onsen on the shore fires fireworks over the water nightly through the summer.

What you actually see

• A circular caldera - about ten kilometres across with wooded islands at its centre.
• Showa-Shinzan - a mountain pushed up out of a field between 1943 and 1945.
• The 2000 eruption trail - buried roads and wrecked buildings left as they fell.
• Nightly fireworks - fired over the lake from boats through the summer.

When to go

May to October. Two days. Summer evenings for the fireworks.

Honest expectations

Toyako Onsen is a dated resort strip and some hotels show it. Winter is long and many facilities close. Volcanic activity can close ropeways and trails at short notice. The lake is often hazy in summer.

Nearby

Noboribetsu Onsen is east; Lake Shikotsu is north-east.