Onuma Park

Mount Komagatake erupted violently in 1640, collapsing its summit and sending debris down the southern slope, which dammed the streams below and created Onuma and Konuma - shallow lakes filled with well over a hundred small islands that are the tops of the buried debris hills. Eighteen of them are linked by short arched footbridges, so the walk is a loop of a kilometre or two hopping from island to island with water on both sides and the truncated cone of Komagatake standing behind. A cycling path of about fourteen kilometres rings the larger lake and is the better way to see it; rowing boats and canoes are for hire. It is thirty minutes by train from Hakodate, which makes it the standard half-day out from the city. In winter the lakes freeze hard enough for skating, snowshoeing and ice fishing for smelt.

What you actually see

• Island hopping on foot - eighteen islets joined by short arched bridges.
• A collapsed volcano - Komagatake, whose 1640 eruption dammed the lakes.
• The ring cycle route - about fourteen kilometres around the larger lake.
• A frozen winter - skating, snowshoes and smelt fishing on the ice.

When to go

May to October; February for the frozen lake. Half a day.

Honest expectations

The bridge loop is short and busy with coach parties in summer. Komagatake's summit route has been restricted for volcanic activity at times. Winter facilities are limited. It is scenic rather than dramatic.

Nearby

Hakodate is south; Lake Toya is north-east along the coast.